Aliphatic-aromatic copolyesters and cellulose ester/polymer blends

ABSTRACT

This invention relates to binary blends of cellulose esters and aliphatic-aromatic copolyesters, cellulose esters and aliphatic polyesters as well as ternary blends of cellulose esters and/or aliphatic polyesters and/or aliphatic-aromatic copolyesters and/or polymeric compounds as well as fibers, molded objects, and films prepared therefrom.

This is a divisional application of application Ser. No. 08/163,441filed on Dec. 7, 1993, U.S. Pat. No. 5,446,079, which is a divisional ofSer. No. 07/797,512 filed on Nov. 21, 1991, now U.S. Pat. No. 5,292,783which issued on Mar. 8, 1994; which is a continuation-in-part of Ser.No. 07/736,262 filed on Jul. 23, 1991, now abandoned; which is acontinuation-in-part of Ser. No. 07/620,225 filed on Nov. 30, 1990, nowabandoned.

FIELD OF INVENTION

This invention concerns binary blends of cellulose esters with aliphaticpolyesters or aliphatic-aromatic copolyesters as well as ternary blendsof cellulose esters with aliphatic polyesters and/or aliphatic-aromaticcopolyesters and/or other polymers. These resins are useful as molded orextruded plastic objects, fibers, or films. This invention also concernsrandom aliphatic-aromatic copolyesters which are useful as molded orextruded plastic objects, fibers, or films. Moreover, various additivescan be added to the blends or to the random aliphatic-aromaticcopolyesters to enhance properties such as water vapor transmissionrates or biodegradability.

BACKGROUND OF THE INVENTION

It is well known that cellulose esters are important as commercialplastics and as fibers. In general, cellulose esters are used in plasticapplications where hard but clear plastics are required. For example,cellulose esters are used in tool handles, eyeglass frames, toys,toothbrush handles, and the like. All of these applications require acombination of high melting and glass transition temperatures as well ashigh modulus and good tensile strength. Formulations based on celluloseesters which provide plastic films with low modulus but good tensilestrength while maintaining sufficient melting and glass transitiontemperatures (Tg) to allow thermal processing are generally unknown.Formulations based on cellulose esters which allow thermal extrusion offibers are also generally unknown.

Because of the high melt temperatures and low melt stability of many ofthe cellulose esters, plasticizers such as dioctyl adipate ortriphenylphosphate are often added to the cellulose ester to lower themelt temperatures during melt processing of the polymer. Although thistechnique is effective, addition of a monomeric plasticizer oftencreates secondary problems related to volatile or extractableplasticizers such as dye drip during melt extrusion or long-termdimensional stability (creep) in an object made from the celluloseester.

The most basic requirement for polymer-polymer miscibility is that thefree energy of mixing be negative (ΔG<0). Although on the surface itwould seem that polymer-polymer miscibility would be common, in realitythere are only a few known miscible binary blends and even fewer knownmiscible ternary blend systems (Brannock, G. R.; Paul, D. R.,Macromolecules, 23, 5240-5250 (1990)). The discovery of miscible binaryor ternary blends is very uncommon.

The classical experimental techniques for determining polymer blendmiscibility involve the determination of the optical clarity of a filmmade from the blend, measurement of the appropriate mechanicalproperties, and measurement of the glass transition temperature by anappropriate thermal analysis technique such as dynamic mechanicalthermal analysis (DMTA) or differential scanning calorimetry (DSC). If ablend is miscible, films made from the blend will generally be clear.Likewise, mechanical properties of a blend, such as tensile strength ortangent modulus, are often intermediate between those of the blendcomponents. Furthermore, a miscible amorphous blend will show a singleTg intermediate between that of the component homopolymers while animmiscible or partially miscible blend will show multiple Tg's. In thecase of a completely immiscible blend, the Tg's will be those of thehomopolymers. For partially miscible blends, the Tg's will beintermediate values corresponding to partially miscible phases rich inone of the components. The variation in binary blend Tg can be modeledby the Fox-Flory equation, Tg₁₂ =Tg₁ (W₁)+Tg₂ (W₂), where Tg₁₂ is the Tgof the blend, Tg₁ and Tg₂ are the Tg's of homopolymers, and W₁ and W₂are the weight percent of each component in the blend. Since the Foxequation does not take into account specific interaction between theblend components the Gordon-Taylor equation, Tg₁₂ =Tg₁ +[kW₂ (Tg₂-Tg₁₂)/W₁ ] where k is a constant, is often preferred in blend analysis.For a homogenous, well mixed system, a plot of Tg₁₂ versus W₂ (Tg₂-Tg₁₂)/W₁ will yield a straight line the slope of which is equal to kand the ordinate intercept will be equal to Tg₁. The constant k is oftentaken as a measure of secondary interactions between the blendcomponents. When k is equal to one, the Gordon-Taylor equation reducesto a simple weight average of the component Tg's.

Miscible blends of cellulose esters and other polymers are generallyunknown. The most notable exceptions include the work disclosed byKoleske, et al. (U.S. Pat. No. 3,781,381 (1973)), Bogan and Combs (U.S.Pat. No. 3,668,157 (1972)), Waniczek et al., (U.S. Pat No. 4,506,045(1985)), and Wingler et al. (U.S. Pat. No. 4,533,397 (1985)). Koleske etal. reported that blends, formed by solution casting of polycaprolactoneand cellulose ester mixtures, are miscible. Later work by Hubbell andCooper (J. Appl. Polym. Sci., 1977, 21, 3035) demonstrated thatcellulose acetate butyrate/polycaprolactone blends are in factimmiscible. Bogan and Combs have reported that block copolymers ofpolyether-polyesters form miscible blends with some cellulose esters.Critical to the invention of Bogan and Combs was the use of anelastomeric block copolymer; they report that the correspondinghomopolymeric elastomers were incompatible with cellulose esters.Waniczek et al., have disclosed that polyester carbonates and polyethercarbonates copolymers form miscible blends with many cellulose estersand are useful as thermoplastic resins. Wingler et al. report thatcontact lenses can be prepared from blends consisting of (A) 97-70% byweight of one or more cellulose esters and (B) 3-30% by weight of analiphatic polymeric compound having ester moieties, carbonate moieties,or both ester and carbonate moieties in the same polymer chain. Theinvention of Wingler et al. is limited to aliphatic polymeric compounds;no reference is made to random copolymers consisting of aliphaticdiacids, aromatic diacids, and suitable diols or polyols. The inventionof Wingler is further limited to cellulose mixed esters having a weightper cent hydroxyl of 1.2% to 1.95% (DS_(OH) =0.11-0.19 where "DS" or"DS/AGU" refers to the number of substituents per anhydroglucose unitwhere the maximum DS/AGU is three). The invention of Wingler et al. isalso limited to binary miscible blends and by the composition range ofthe blends (3-30% aliphatic polymeric compound). No reference is made toblends containing an immiscible component where the immiscible componentis useful for enhancing properties such as water vapor transmissionrates or biodegradability. Immiscible blends of cellulose esters andaromatic polyesters have also been disclosed by Pollock et al. (U.S.Pat. No. 4,770,931 (1988)) which are useful in applications such aspaper substitutes.

One time use, disposable items are common. Examples of such disposablearticles include items such as infant diapers, incontinence briefs,sanitary napkins, tampons, bed liners, bedpans, bandages, food bags,agricultural compost sheets, and the like. Examples of other disposableitems include razor blade handles, toothbrush handles, disposablesyringes, fishing lines, fishing nets, packaging, cups, clamshells, andthe like. For disposable items, environmental non-persistence isdesirable.

Disposable articles are typified by disposable diapers. A disposablediaper typically has a thin, flexible polyethylene film cover, anabsorbent filler as the middle layer, and a porous inner liner which istypically nonwoven polypropylene. The diaper construction also requirestabs or tape for fastening the diaper (typically polypropylene) as wellas various elastomers and adhesives. Although the absorbent filler isusually biodegradable or easily dispersed in an aqueous environment,currently neither the outer or inner liner nor the other parts such asthe tabs or adhesives will degrade from microbial action. Consequently,disposable absorbent materials such as diapers accumulate in landfillsand place enormous pressure on waste systems. Other disposable articlessuch as plastic bags or plastic compost sheets suffer from similarproblems.

Numerous studies have demonstrated that cellulose or cellulosederivatives with a low degree of substitution, i.e., less than one, arebiodegradable. Cellulose is degraded in the environment by bothanaerobic or aerobic microorganisms. Typical endproducts of thismicrobial degradation include cell biomass, methane(anaerobic only),carbon dioxide, water, and other fermentation products. The ultimateendproducts will depend upon the type of environment as well as the typeof microbial population that is present. However, it has been reportedthat cellulose esters with a DS greater than about one are completelyresistant to attack by microorganisms. For example, Stutzenberger andKahler (J. Appl. Bacteriology, 66, 225 (1986)) have reported thatcellulose acetate is extremely recalcitrant to attack by Thermomonosporacurvata.

Polyhydroxyalkanoates (PHA), such as polyhydroxybutyrate (PHB),polycaprolactone (PCL), or copolymers of polyhydroxybutyrate andpolyhydroxyvalerate (PHBV), have been known for at least twenty years.With the exception of polycaprolactone, they are generally preparedbiologically and have been reported to be biodegradable (M. Kunioka etal., Appl. Microbiol. Biotechnol., 30, 569 (1989)).

Polyesters prepared from aliphatic diacids or the correspondingcarboxylic ester of lower alcohols and diols have also been reported tobe biodegradable. For example, Fields and Rodriguez ("Proceedings of theThird International Biodegradation Symposium", J. M. Sharpley and A. M.Kaplan, Eds., Applied Science, Barking, England, 1976, p. 775) preparedpolyesters from C2-C12 diacids coupled with C4-C12 diols and found thatmany were biodegradable.

Aliphatic polyesters have been used in very few applications mainlybecause of their low melting points and low glass transitiontemperatures (generally less than 65° C. and -30° C., respectively). Atroom temperature, the physical form of many of the aliphatic polyestersis as a thick, viscous liquid. Therefore, aliphatic polyesters are notexpected to be generally useful.

On the other hand, aromatic polyesters, such as poly(ethyleneterephthalate), poly(cyclohexanedimethanol terephthalate), andpoly(ethylene terephthalate-co-isophthalate), have proven to be veryuseful materials. Aromatic polyesters, however, are generally veryresistant to biodegradation (J. E. Potts in "Kirk-Othmer Encyclopedia ofChemical Technology", Suppl. Vol, Wiley-Interscience, New York, 1984,pp. 626-668). Block copolyesters containing both aliphatic and aromaticstructures have been prepared and have been shown to be biodegradable.Examples of aliphatic-aromatic block copolyester-ethers include the workof Reed and Gilding (Polymer, 22, 499 (1981)) using poly(ethyleneterephthalate)/poly(ethylene oxide) where these block copolymers werestudied and found to be biodegradable in vitro. Tokiwa and Suzuki haveinvestigated block copolyesters such as those derived frompoly(caprolactone) and poly(butylene terephthalate) and found them to bedegraded by a lipase (J. Appl. Polym. Sci., 26, 441-448 (1981)).Presumably, the biodegradation is dependent upon the aliphatic blocks ofthe copolyesters; the blocks consisting of aromatic polyester are stillresistant to biodegradation. Random aliphatic-aromatic copolyesters havenot been investigated in this regard.

While random copolyesters with low levels of aliphatic diacids are known(e.g., Droscher and Horlbeck, Ange. Makromol. Chemie, 128,203-213(1984)), copolyesters with high levels (>30%) of aliphaticdicarboxylic components are generally unknown. Copolyesters with as muchas 40% aliphatic dicarboxylic acid components have been disclosed inadhesive applications; however, these copolyesters adhesives contain atleast two dialcohol components in order to achieve the desired adhesiveproperties (Cox, A., Meyer, M. F., U.S. Pat. No. 4,966,959 (1990)).

There are many references to the preparation of films from polymers suchas polyhydroxybutyrate (PHB). Production of films from PHB generallyinvolves solvent casting principally because PHB polymers tend to remainsticky or tacky for a substantial time after the temperature has droppedbelow the melting point of the PHB. To circumvent this problem, Martiniet al. (U.S. Pat. Nos. 4,826,493 and 4,880,592) teach the practice ofco-extruding PHB with a thermoplastic that is non-tacky. Suchthermoplastics remain as a permanent layer on the PHB film or may be asacrificial film which is removed following extrusion.

PHB has also been reported to be useful in the preparation of disposablearticles. Potts (U.S. Pat. Nos. 4,372,311 and 4,503,098) has disclosedthat water soluble polymers such as poly(ethylene oxide) may be coatedwith biodegradable water insoluble polymers such as PHB. In theseinventions, the PHB layer, which is distinct from the water solublelayer, degrades exposing the water soluble layer which will thendisperse in an aqueous environment.

There have been other reports of the preparation of a biodegradablebarrier film for use in disposable articles. Comerford et al. (U.S. Pat.No. 3,952,347) have disclosed that finely divided biodegradablematerials such as cellulose, starch, carbohydrates, and natural gums maybe dispersed in a matrix of nonbiodegradable film forming materialswhich are resistant to solubility in water. Wielicki (U.S. Pat. No.3,602,225) teaches the use of barrier films made of plasticizedregenerated cellulose films. Comerford (U.S. Pat. No. 3,683,917) teachesthe use of a cellulosic material coated with a water repellent material.

There exists in the market place the need for thermoplastics which areuseful in molding, fiber, and film applications. For these applications,it is desirable that the thermoplastic blend be processable at a lowmelt temperature and have a high glass transition temperature. Thesethermoplastics should not contain volatile or extractable plasticizers.Moreover, there is a need in the marketplace for a biodegradablematerial for use in disposable articles such as diapers, razors, and thelike. As an example, unlike films prepared from polymers such as PHB,the material should be amenable to both solvent casting and meltextrusion. In melt extruding this material, coextrusion with otherthermoplastics should not be a requirement. The barrier properties ofthis new biodegradable material should be adequate so that coating witha water insoluble polymer is not required. The new material shoulddisperse completely in the environment and not require coating with awater soluble polymer. The mechanical properties of the material shouldbe such that films of low modulus but of high tensile strength can beprepared.

SUMMARY OF THE INVENTION

The present invention, in part, concerns binary blends of celluloseesters and aliphatic-aromatic copolyesters, cellulose esters andaliphatic polyesters as well as ternary blends of cellulose estersand/or aliphatic polyesters and/or aliphatic-aromatic copolyestersand/or polymeric compounds as well as fibers, molded objects, and filmsprepared therefrom which have one or more of the above or belowdescribed desirable properties. More specifically, the present inventionis directed to a blend comprising:

I. (A) about 5% to about 98% of a C1-C10 ester of cellulose having aDS/AGU of about 1.7 to 3.0 and an inherent viscosity of about 0.2 toabout 3.0 deciliters/gram as measured at a temperature of 25° C. for a0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane, and

(B) about 2% to about 95% of a aliphatic-aromatic copolyester having aninherent viscosity of about 0.2 to about 2.0 deciliters/gram as measuredat a temperature of 25° C. for a 0.5 g sample in 100 ml of a 60/40 partsby weight solution of phenol/tetrachloroethane, said percentages beingbased on the weight of component (A) plus component (B);

II. (A) about 5% to about 98% of a C1-C10 ester of cellulose having aDS/AGU of about 1.7 to 2.75 and an inherent viscosity of about 0.2 toabout 3.0 deciliters/gram as measured at a temperature of 25° C. for a0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane, and

(B) about 2% to about 95% of a aliphatic polyester having an inherentviscosity of about 0.2 to about 2.0 deciliters/gram as measured at atemperature of 25° C. for a 0.5 g sample in 100 ml of a 60/40 parts byweight solution of phenol/tetrachloroethane, said percentages beingbased on the weight of component (A) plus component (B);

III. (A) about 4% to about 97% of a C1-C10 ester of cellulose having aDS/AGU of about 1.7 to 3.0 and an inherent viscosity of about 0.2 toabout 3.0 deciliters/gram as measured at a temperature of 25° C. for a0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane,

(B) about 2% to about 95% of an aliphatic polyester and/or analiphatic-aromatic copolyester having an inherent viscosity of about 0.2to about 2.0 deciliters/gram as measured at a temperature of 25° C. fora 0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane,

(C) about 1% to about 94% of immiscible, partially miscible, or misciblepolymeric compounds having an inherent viscosity of about 0.2 to about2.0 deciliters/gram as measured at a temperature of 25° C. for a 0.5 gsample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane, said percentages being based on the weight ofcomponent (A) plus component (B) plus component (C);

IV. (A) about 50% to about 99% of a binary blend of (I) or (II) or aternary blend of (III) having an inherent viscosity of about 0.4 toabout 3.0 deciliters/gram as measured at a temperature of 25° C. for a0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane,

(B) about 1% to about 50% of biodegradable additives, said percentagesbeing based on the weight of component (A) plus component (B);

V. (A) about 95% to about 99.95% of a binary blend of (I) or (II) or aternary blend of (III) having an inherent viscosity of about 0.4 toabout 3.0 deciliters/gram as measured at a temperature of 25° C. for a0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane,

(B) about 0.05% to about 5% of immiscible hydrophobic agent, saidpercentages being based on the weight of component (A) plus component(B).

The present invention is also directed to:

VI. An essentially linear, random, semicrystalline aliphatic-aromaticcopolyester which has an inherent viscosity of about 0.5 to 1.8deciliters/gram as measured at a temperature of 25° C. for a 0.5 gsample in 100 mL of a 60/40 parts by weight solution ofphenol/tetrachloroethane and has a melting point between 75° C. and 160°C.

VII. A mixture of 50 to 99% of (VI) and about 1% to about 50% ofbiodegradable additives, said percentages being based on the weight ofcomponent (VI) plus biodegradable additives.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A--Scanning electron microscopy (SEM) photograph of the outer,smooth surface of a cellulose acetate (DS=1.7) film formed by drawing afilm from a 20 wt. % solution of cellulose acetate in a 50/50(vol./vol.) mixture of water/acetone. Magnification is 200×.

FIG. 1B--SEM photograph of the outer, smooth surface of a celluloseacetate (DS=1.7) film formed by drawing a film from a 20 wt. % solutionof cellulose acetate in a 50/50 (vol./vol.) mixture of water/acetoneafter four days incubation in an in vitro microbial enrichment system.Magnification is 200×.

FIG. 2A--SEM photograph of the inner, rough surface of a celluloseacetate (DS=1.7) film formed by drawing a film from a 20 wt. % solutionof cellulose acetate in a 50/50 (vol./vol.) mixture of water/acetone.Magnification is 300×.

FIG. 2B--SEM photograph of the inner, rough surface of a celluloseacetate (DS=1.7) film formed by drawing a film from a 20 wt. % solutionof cellulose acetate in a 50/50 (vol./vol.) mixture of water/acetoneafter four days incubation in an in vitro microbial enrichment system.Magnification is 300×.

FIG. 3--SEM photograph of the outer, smooth surface of a celluloseacetate (DS=1.7) film formed by drawing a film from a 20 wt. % solutionof cellulose acetate in a 50/50 (vol./vol.) mixture of water/acetoneafter four days incubation in an in vitro microbial enrichment systemfrom which the bacteria has not been washed. Magnification is 4,000×.

FIG. 4--SEM photograph of the inner, rough surface of a celluloseacetate (DS=1.7) film formed by drawing a film from a 20 wt. % solutionof cellulose acetate in a 50/50 (vol./vol.) mixture of water/acetoneafter four days incubation in an in vitro microbial enrichment systemfrom which the bacteria have not been washed. Magnification is 4,000×.

FIG. 5--The type of cylinder used for suspending film strips inwastewater basins. Strips of film 0.5 inch wide and 6 inches long ofknown weight and thickness were placed in the cylinder which wasattached to a steel cable and immersed in a wastewater basin.

DETAILED DESCRIPTION OF THE INVENTION

We have found that cellulose esters form binary blends with aliphaticpolyesters and aliphatic-aromatic copolyesters as well as ternary blendswith aliphatic polyesters/polyacrylates, aliphatic polyesters/polyvinylacetates, aliphatic polyesters/polyvinyl alcohol, aliphaticpolyesters/polyvinyl chloride, aliphatic polyesters/polycarbonates,aliphatic polyesters/polyvinyl acetate-polyethylene copolymer, aliphaticpolyesters/cellulose ethers, aliphatic polyesters/polyamides,aliphatic-aromatic copolyesters/polyacrylates, aliphatic-aromaticcopolyesters/polyvinyl acetates, aliphatic-aromaticcopolyesters/polyvinyl alcohol, aliphatic-aromaticcopolyesters/polyvinyl chloride, aliphatic-aromaticcopolyesters/polycarbonates, aliphatic-aromatic copolyesters/polyvinylacetate-polyethylene copolymer, aliphatic-aromaticcopolyesters/cellulose ethers, or aliphatic-aromaticcopolyesters/polyamides, as well as other polymers, to produce resinswhich are useful as molded or extruded plastic objects, fibers, orfilms. Moreover, various additives can be added to the blend to enhanceproperties such as water vapor transmission rates or biodegradability.

The cellulose esters of the present invention generally compriserepeating units of the structure: ##STR1## wherein R¹, R², and R³ areselected independently from the group consisting of hydrogen or straightchain alkanoyl having from 2 to 10 carbon atoms.

The cellulose esters useful in formulating the blend can be a cellulosetriester or a secondary cellulose ester. Examples of cellulose triestersinclude cellulose triacetate, cellulose tripropionate, or cellulosetributyrate. Examples of secondary cellulose esters include celluloseacetate, cellulose acetate propionate, and cellulose acetate butyrate.These cellulose esters are described in U.S. Pat. Nos. 1,698,049;1,683,347; 1,880,808; 1,880,560; 1,984,147, 2,129,052; and 3,617,201,incorporated herein by reference in their entirety.

The cellulose esters useful in the present invention can be preparedusing techniques known in the art or are commercially available, e.g.,from Eastman Chemical Company, Inc., Kingsport, Tenn., U.S.A.

The cellulose esters useful in the present invention have at least 2anhydroglucose rings and typically have between 2 and 5,000anhydroglucose rings; also, such polymers typically have an inherentviscosity (IV) of about 0.2 to about 3.0 deciliters/gram, preferablyabout 1 to about 1.5, as measured at a temperature of 25° C. for a 0.5gram sample in 100 ml of a 60/40 by weight solution ofphenol/tetrachloroethane. In addition, the DS/AGU of the celluloseesters useful herein ranges from about 1.7 to about 3.0. Preferredesters of cellulose include cellulose acetate (CA), cellulose propionate(CP), cellulose butyrate (CB), cellulose acetate propionate (CAP),cellulose acetate butyrate (CAB), cellulose propionate butyrate (CPB),and the like. CAP and CAB are more preferred cellulose esters. The mostpreferred ester of cellulose is CAP.

For binary blends, the preferred esters of cellulose for blending withaliphatic-aromatic copolyesters are CAP and CAB. The preferred ester ofcellulose is CAP having a DS/AGU of 2.1-2.85 wherein the DS/AGU ofacetyl ester is 1-50% of the total ester content. The most preferredCAP's have a DS/AGU of 2.5-2.75 wherein the DS/AGU of acetyl ester is4-30% of the total ester content.

For binary blends, the preferred esters of cellulose for blending withaliphatic polyesters are CA, CAP, and CAB. A preferred ester ofcellulose is CA having a DS/AGU of 1.7-2.75. Another preferred ester ofcellulose is CAP having a DS/AGU of 1.7-2.75 wherein the DS/AGU ofacetyl ester is 1-50% of the total ester content. The most preferredCAP's have a DS/AGU of 2.1-2.6 wherein the DS/AGU of acetyl ester is4-30% of the total ester content. It is also preferred that the CAP'shave a glass transition temperature (Tg) of about 140° C. to 180° C.

For ternary blends, the preferred esters of cellulose for blending withaliphatic polyesters and/or aliphatic-aromatic copolyesters and/orpolymeric compounds, biodegradable additives, or hydrophobic agents areCAP and CAB. The preferred ester of cellulose is CAP having a DS/AGU of1.7-3.0 wherein the DS/AGU of acetyl ester is 1-50% of the total estercontent. The most preferred CAP's have a DS/AGU of 2.5-2.75 wherein theDS/AGU of acetyl ester is 4-30% of the total ester content.

The aliphatic-aromatic copolyesters that are useful in blends in thepresent invention are random copolymers and preferably comprisesrepeating units of: ##STR2## wherein R⁴ and R⁷ are selected from one ormore of the following groups consisting of C₂ -C₁₂ alkylene oroxyalkylene; C₂ -C₁₂ alkylene or oxyalkylene substituted with one tofour substituents independently selected from the group consisting ofhalo, C₆ -C₁₀ aryl, and C₁ -C₄ alkoxy; C₅ -C₁₀ cycloalkylene; C₅ -C₁₀cycloalkylene substituted with one to four substituents independentlyselected from the group consisting of halo, C₆ -C₁₀ aryl, and C₁ -C₄alkoxy; R⁵ is selected from one or more of the following groupsconsisting of C₀ -C₁₂ alkylene or oxyalkylene; C₁ -C₁₂ alkylene oroxyalkylene substituted with one to four substituents independentlyselected from the group consisting of halo, C₆ -C₁₀ aryl, and C₁ -C₄alkoxy; C₅ -C₁₀ cycloalkylene; and C₅ -C₁₀ cycloalkylene substitutedwith one to four substituents independently selected from the groupconsisting of halo, C₆ -C₁₀ aryl, and C₁ -C₄ alkoxy; R⁶ is selected fromone or more of the following groups consisting of C₆ -C₁₀ aryl, C₆ -C₁₀aryl substituted with substituted with one to four substituentsindependently selected from the group consisting of halo, C₁ -C₄ alkyl,and C₁ -C₄ alkoxy.

It is preferred that said aliphatic-aromatic copolyester comprises 10 to1,000 repeating units. Most preferred is when said aliphatic-aromaticcopolyester comprises 15 to 600 repeating units.

In the present invention, the mole % of R⁵ in the copolymer can rangefrom 30 to 95%, and the mole % of R⁶ can range from 5 to 70%. A morepreferred range is when the mole % of R⁵ is from about 45 to 85% and themole % of R⁶ is from about 15-55 mol %. The most preferred ranges, ingeneral, depend upon the needed level of miscibility of the copolyesterwith the cellulose esters and the physical properties desired. The mostpreferred ranges for miscible blends is when R⁵ is glutaric and the mole% of R⁵ in the copolyester ranges from 70 to 85% and the mole % of R⁶range from 15-30 mol %. The most preferred ranges for partially miscibleblends is when R⁵ is glutaric and the mol % of R⁵ in the copolyesterranges from 45 to 60% and the mole % of R⁶ ranges from 40-55 mol %. Therange of miscibility of a particular blend can change as the molecularweight of a blend component is changed. In general, analiphatic-aromatic polyester having a lower molecular weight or inherentviscosity will be more miscible with a given cellulose ester relative tothe higher molecular weight polyester.

It is preferred that the aliphatic-aromatic copolyester has an inherentviscosity of about 0.4 to about 1.2 as measured at a temperature of 25°C. for a 0.5 gram sample in 100 ml of a 60/40 by weight solution ofphenol/tetrachloroethane.

As used herein the terms "alkyl" and "alkylene" refer to either straightor branched chain moieties such as --CH₂ --CH₂ --CH₂ --CH₂ -- and --CH₂CH(X)--CH₂ --. Also, all of the carbon atoms of the cycloalkyl andcycloalkylene moieties are not necessarily in the ring structure, e.g.,a C₈ cycloalkyl group can be cyclooctyl or dimethylcyclohexyl. The term"oxyalkylene" refers to alkylene chains containing from 1 to 4 etheroxygen groups.

One type of aliphatic polyesters useful in the present inventionpreferably comprises repeating units of: ##STR3## wherein R⁸ is selectedfrom one or more of the following groups consisting of C₂ -C₁₂ alkyleneor C₂ -C₁₂ oxyalkylene; C₂ -C₁₂ alkylene or C₂ -C₁₂ oxyalkylenesubstituted with one to four substituents independently selected fromthe group consisting of halo, C₆ -C₁₀ aryl, and C₁ -C₄ alkoxy; C₅ -C₁₀cycloalkylene; C₅ -C₁₀ cycloalkylene substituted with one to foursubstituents independently selected from the group consisting of halo,C₆ -C₁₀ aryl, and C₁ -C₄ alkoxy; R⁹ is selected from one or more of thefollowing groups consisting of C₀ -C₁₂ alkylene or oxyalkylene; C₁ -C₁₂alkylene or oxyalkylene substituted with one to four substituentsindependently selected from the group consisting of halo, C₆ -C₁₀ aryl,and C₁ -C₄ alkoxy; C₅ -C₁₀ cycloalkylene; and C₅ -C₁₀ cycloalkylenesubstituted with one to four substituents independently selected fromthe group consisting of halo, C₆ -C₁₀ aryl, and C₁ -C₄ alkoxy.

It is preferred that R⁸ is C₂ -C₆ alkylene, C₄ -C₈ oxyalkylene, or C₅-C₁₀ cycloalkylene; and R⁹ is C₀ -C₁₀ alkylene, C₂ oxyalkylene or C₅-C₁₀ cycloalkylene.

It is more preferred that R⁸ is C₂ -C₄ alkylene, C₄ -C₈ oxyalkylene, orC₅ -C₁₀ cycloalkylene; and R⁹ is C₂ -C₄ alkylene, C₂ oxyalkylene or C₅-C₁₀ cycloalkylene.

It is preferred that said aliphatic polyester comprises 10 to 1,000repeating units. Most preferred is when said aliphatic polyestercomprises 15 to 600 repeating units. The terms "alkyl" and "alkylene"are as defined above.

A second type of aliphatic polyester are polyhyroxyalkanoates which arecomprised of repeat units of the following structure: ##STR4## wherein mis an integer of 0 to 10, and R¹⁰ is selected from the group consistingof hydrogen; C₁ -C₁₂ alkyl; C₁ -C₁₂ alkyl substituted with one to foursubstituents independently selected from the group consisting of halo,C₆ -C₁₀ aryl, and C₁ -C₄ alkoxy; C₅ -C₁₀ cycloalkyl; and C₅ -C₁₀cycloalkyl substituted with one to four substituents independentlyselected from the group consisting of halo, C₆ -C₁₀ aryl, and C₁ -C₄alkoxy.

For the purpose of this invention aliphatic polyester is defined as analiphatic polyester which does not contain significant quantities ofcarbonate linkages. Furthermore, polyester is defined as a polyesterprepared by a condensation process or by a biological process.

Typical polymeric compounds for ternary blends include polyacrylatessuch as polymethyl methacrylate (PMMA), polyethyl methacrylate (PEMA),or copolymers thereof such as those which are commercially availablefrom Rohm and Haas. Polyvinyl acetate, polyvinyl alcohol, polyvinylchloride, and polyvinyl acetate-polyethylene copolymers are also usefulin ternary blends and are common commercial polymers which are availablefrom companies such as Air Products and Chemicals, Inc. Polycarbonates,available from GE Plastics, are also useful in ternary blends. Celluloseethers are commercially available from companies such as Aqualon Co. andare also useful in ternary blends. Polyamides, e.g., nylon 6 which isavailable from Ashley Polymers, Inc., is also highly useful in ternaryblends. For this invention, preferred polyacrylates are PMMA. Thepreferred polyvinyl alcohols are those that are 5-60% hydrolyzed andhave a molecular weight of 1,000 to 30,000. The preferred celluloseesters are hydroxypropyl cellulose (HPC) and hydroxypropyl methylcellulose (HPMC). The preferred polyvinyl acetate will have a molecularweight of 1,000 to 1,000,000.

Typical biodegradable additives for binary and ternary blends of thisinvention include microcrystalline cellulose, cellulose monoacetate,starch and other carbohydrates. The preferred materials aremicrocrystalline cellulose, available from FMC, or starch, availablefrom National Starch Co., which typically have a particle size of 1-200microns; the preferred particle size is 0.1-15 microns. Also preferredare cellulose monoacetates which have a DS/AGU of 1.2 to 0.4 and will beeither water soluble or water swellable (U.S. patent application Ser.Nos. 509,385; 509,400 (1990)).

Typical immiscible hydrophobic agents include paraffin, monoacylcarbohydrates, and monoglycerides. An example of a monoacyl carbohydrateis 6-O-sterylglucopyranoside. The preferred hydrophobic agents aremonoglycerides containing C12-C18 fatty acids. These monoglyceridescontaining C12-C18 fatty acids may also be optionally acylated with5-95% acetyl, propionyl, butyryl, or succinyl groups. The more preferredmonoglycerides are those containing C16-C18 fatty acids. The mostpreferred hydrophobic agent is glyceryl monostearate.

The preparation of polyesters and copolyesters is well known in the art(U.S. Pat. No. 2,012,267, incorporated herein by reference in itsentirety). Such reactions are usually carried out at temperatures from150° C. to 300° C. in the presence of polycondensation catalysts such astitanium tetrachloride, manganese diacetate, antimony oxide, dibutyl tindiacetate, zinc chloride, or combinations thereof. The catalysts aretypically employed in amounts between 10 to 1000 ppm, based on totalweight of the reactants. For the purpose of the present invention, arepresentative aliphatic polyester is the polycondensation product ofdimethylglutarate and 1,6-hexanediol. This polyester, poly(hexamethyleneglutarate), is produced when dimethylglutarate and 1,6-hexanediol areheated at approximately 210° C. for 4 hours and then at 260° C. for 1.5hours under vacuum in the presence of 100 ppm of Ti. A representativealiphatic-aromatic copolyester is poly(tetramethyleneglutarate-co-terephthalate) containing 30 mole per cent terephthalate.This polyester is produced when dimethylglutarate, dimethylterephthalate, and 1,4-butanediol are heated at 200° C. for 1 hour thenat 245° C. for 0.9 hour under vacuum in the presence of 100 ppm of Tipresent initially as Ti(O^(i) Pr)₄.

It is preferred that said aliphatic-aromatic copolyester for use inblending is prepared from any polyester forming combination ofdicarboxylic acids or derivatives thereof, and diols. Said dicarboxylicacids are selected from the group consisting of the following diacids:malonic, succinic, glutaric, adipic, pimelic, azelaic, sebacic, fumaric,2,2-dimethyl glutaric, suberic, 1,3-cyclopentanedicarboxylic,1,4-cyclohexanedicarboxylic, 1,3-cyclohexanedicarboxylic, diglycolic,itaconic, maleic, 2,5-norbornanedicarboxylic, 1,4-terephthalic,1,3-terephthalic, 2,6-naphthoic, 1,5-naphthoic, and ester formingderivatives thereof, and combinations thereof; and said diols areselected from the group consisting of ethylene glycol, diethyleneglycol, propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol,1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,2,2,4-trimethyl-1,6-hexanediol, thiodiethanol,1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, triethylene glycol,tetraethylene glycol, and combinations thereof.

Specific examples of preferred aliphatic-aromatic copolyesters forblending include poly(tetramethyleneglutarate-co-terephthalate-co-diglycolate) [50/45/5],poly(tetramethylene glutarate-co-terephthalate) [50/50],poly(tetramethylene glutarate-co-terephthalate) [60/40],poly(tetramethylene glutarate-co-terephthalate) [70/30],poly(tetramethylene glutarate-co-terephthalate) [85/15], poly(ethyleneglutarate-co-terephthalate) [70/30], poly(tetramethyleneadipate-co-terephthalate) [85/15], poly(tetramethylenesuccinate-co-terephthalate) [85/15], and poly(tetramethylene-co-ethyleneglutarate-co-terephthalate) [50/50,70/30].

The aliphatic-aromatic copolyesters (referred to as AAPE herein) thatare useful in the present invention without requiring blending of asignificant amount of another component are essentially linear, randomcopolymers and preferably comprise repeating units of: ##STR5## whereinR¹¹ and R¹² are the same and are selected from the groups consisting ofC2-C8 alkylene or oxylalkylene; R¹³ is selected from one or more of thegroups consisting of C0-C8 alkylene or C2-C4 oxyalkylene, and the mole %of R¹³ is from about 95-35%; R¹⁴ is selected from the group of C6-C10aryl, and the mole % of R¹⁴ is from about 5-65%. More preferred AAPE arethose wherein R¹¹ and R¹² are the same and are selected from C2-C4alklyene; R¹³ is selected from one or more of the groups consisting ofC2-C6 alkylene or C2 oxyalkylene, and the mole % of R¹³ is from about95-40%; R¹⁴ is 1,4-disubstituted-C6 aryl, and the mole % of R¹⁴ is fromabout 5-60%. The most preferred compositions for these AAPE are thoseprepared from the following diols and diacids (or polyester formingderivatives thereof) in the following mole %:

(1) Glutaric acid (30-65%); diglycolic acid (0-10 mol %); terephthalicacid (25-60%); 1,4-butanediol (100 mole %).

(2) Succinic acid (30-85%); diglycolic acid (0-10%); terephthalic acid(5-60%); 1,4-butanediol (100 mole %).

(3) Adipic acid (30-65%); diglycolic acid (0-10%); terephthalic acid(25-60%); 1,4-butanediol (100 mole %).

Specific examples of preferred AAPE for applications where blending isnot required include poly(tetramethyleneglutarate-co-terephthalate-co-diglycolate) [50/45/5],poly(tetramethylene glutarate-co-terephthalate) [50/50],poly(tetramethylene glutarate-co-terephthalate) [60/40],poly(tetramethylene glutarate-co-terephthalate) [40/60],poly(tetramethylene succinate-co-terephthalate) [85/15], poly(ethylenesuccinate-co-terephthalate) [70/30], poly(tetramethyleneadipate-co-terephthalate) [85/15], and poly(tetramethylenesuccinate-co-terephthalate) [70/30].

It is preferred that said aliphatic polyester is prepared from anypolyester forming combination of the following:

(i) hydroxy acids,

(ii) dicarboxylic acids or derivatives thereof, and

(iii) diols.

Said hydroxy acids are selected from the group consisting of4-(hydroxymethyl)cyclohexanecarboxylic acid, hydroxypivalic acid,6-hydroxyhexanoic acid, glycolic acid, lactic acid, ester formingderivatives thereof, and combinations thereof; said dicarboxylic acidsare selected from the group consisting of the following diacids:malonic, succinic, glutaric, adipic, pimelic, azelaic, sebacic, fumaric,2,2-dimethyl glutaric, suberic, 1,3-cyclo-pentanedicarboxylic,1,4-cyclohexanedicarboxylic, 1,3-cyclohexanedicarboxylic, diglycolic,itaconic, maleic, 2,5-norbornanedicarboxylic, ester forming derivativesthereof, and combinations thereof; and said diols are selected from thegroup consisting of ethylene glycol, propylene glycol, 1,3-propanediol,2,2-dimethyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol,1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol,thiodiethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, diethylene glycol, triethyleneglycol, tetraethylene glycol, and combinations thereof.

Specific examples of preferred aliphatic polyesters include,polyhydroxybutyrate, a copolymer of polyhydroxybutyrate andpolyhydroxyvalerate, poly(hexamethylene glutarate), poly(hexamethyleneadipate), poly(ethylene sebacate), poly(tetramethylene glutarate),poly(tetramethylene adipate), poly(tetramethylene sebacate),poly(ethylene glutarate), poly(ethylene succinate), poly(tetramethylenesuccinate), or poly(ethylene adipate).

Other aliphatic polyesters useful in the present invention arepolyhydroxyalkanoates that are derived from biological sources. A numberof laboratories (cf. Makromol. Chem., 191, 1957-1965 (1990); J.Bacteriol., 154, 870 (1983); Macromolecules, 22, 1106 (1989)) havedemonstrated that microorganisms, e.g., Pseudomonas oleovorans,Alcaligenes eutrophus, Bacillus megaterium, Rhodospirillum rubrum, canaccumulate polyhydroxyalkanoates containing alkyl pendant groups whengrown on either n-alkanes or n-alkanoic acids under nutrient limitingconditions. In the case of P. oleovorans, a polyhydroxyalkanoate with aphenyl pendant group can be produced. The polymer forms as intracellulargranules which provides the cell with a reserve of fatty acid in a formthat is osmotically inert. When the microorganism is faced with energyor starvation conditions the polymer is degraded as a food source;hence, bacterial polyhydroxyalkanoates are inherently biodegradable.

Polyhydroxyalkanoates derived from biological sources are rarelyhomopolymers. During biosynthesis, carbon segments, typically two carbonfragments, are either removed or added to the original alkanoateresulting in the formation of a copolymer (Int. J. Biol. Macromol., 11,49-55 (1989)). For example, when P. oleovorans is fed either n-octane orn-octanoic acid as the only carbon source, the product produced is acopolymer which contains mostly C6 and C8 units.

Any of the blends, AAPEs, films, plastic objects, and fibers of theinvention can optionally additionally comprise 0.001 to 50 weight percent, based on the total weight of the composition, of at least oneadditional additive selected from a non-polymeric plasticizer, a thermalstabilizer, an antioxidant, a pro-oxidant, an acid scavenger, anultraviolet light stabilizer, a promoter of photodegradation,inorganics, and colorants. Typical non-polymeric plasticizers includedioctyl adipate, phosphates, and diethyl phthalate. Representativeinorganics include talc, TiO₂, CaCO₃, NH₄ Cl, and silica. Colorants canbe monomeric, oligomeric, and, of course, polymeric. Preferred polymericcolorants are aliphatic polyesters, aliphatic-aromatic copolyesters, oraromatic polyesters in which the color producing monomer, i.e., a dye,is covalently incorporated into the polymer. Such representativepolymeric colorants are described by Weaver et al. in U.S. Pat. Nos.4,892,922, 4,892,923, 4,882,412, 4,845,188, 4,826,903, and 4,749,773 andare incorporated herein by reference in their entirety. These polymericdyes are represented by poly(tetramethylene terephthalate) containing10% 1,5-bis(O-carboxyanilino) anthraquinone.

Of course, it is also preferred, but not required, that the blends ofthe invention, as well as the films, plastic objects, and fibersprepared from the blends, be compatible and/or biodegradable. Thepreferred blends, films, plastic objects, and fibers are compatible asevidenced by improved mechanical properties, having a single Tg, and/orbeing substantially clear or substantially non-hazy. It is alsopreferred, but not required, that the AAPE, as well as the films,plastic objects, and fibers prepared from the AAPE be biodegradable.

Films made from the blends have good tensile properties and can be veryflexible depending upon the type of cellulose ester and aliphaticpolyesters, aliphatic-aromatic copolyesters, and/or polymeric compoundselected. Many of the films have good optical properties, i.e., arepreferably substantially clear; the films can also contain significantquantities of colorant (i.e., pigment or dye). Because these films cancontain dyes or pigments, extensive purification of PHA, such as PHB, toremove cellular material is not required.

For film used in environmentally non-persistent applications, it ispreferred that the blend used to make the film be comprised of acellulose ester with a DS of (2.1-2.75) and with a high Tg (140°-180°C.). Since the blends of this invention generally exhibit a Tg which canbe predicted from the equation, Tg₁₂ =Tg₁ W%₁ +Tg₂ W%₂, use of acellulose ester with a higher Tg permits the incorporation of morepolyester into the blend than is possible when using a cellulose esterwith a lower Tg while still maintaining equivalent blend Tg's. Moreover,we have surprisingly found that because the lower DS cellulose estergenerally has a higher modulus, incorporation of more polyester in theblend with the low DS cellulose ester leads to films with equivalentmechanical properties to films made from blends composed of a celluloseester with a lower Tg and lower polyester content. Incorporation of morepolyester in the blend is highly desirable since the blends with higherpolyester content will biodegrade at a faster rate.

Of course, many of the AAPEs of this invention which do not requireblending are also useful in film applications. While these AAPE do nothave as high as a melting point as poly(ethylene terephthalate), theAAPE have higher melting points that are generally observed withaliphatic polyesters and are therefore useful in many applications,particularly those requiring biodegradability. Succinic acid based AAPEsshow particularly good utility in these applications due to theirrelatively high melting points. These copolyesters have been shown to bedegradable even though they are semicrystalline and contain substantialamounts of aromatic groups. Furthermore, diglycolic acid has been foundto be a useful comonomer for these AAPE because it aids in the initialbreakup of the films.

These AAPEs are also particularly useful in molded parts, extrudedobjects, fibers, non-wovens, and foamed objects which benefit from beingbiodegradable. Films and fibers made from these copolyesters can beoriented. Orientation in many of these copolymers (especially thosecontaining 1,4-butanediol) is accompanied by improved physicalproperties and a change from being opaque to being clear. AAPE films canbe oriented uniaxially or biaxially and can be oriented in a blown filmoperation.

The blends and/or AAPE of this invention are useful in packagingapplications where thin films are desirable. Many of the blends and/orAAPE of this invention are particularly useful as thin barrier filmswhere they must function as a barrier and/or be biodegradable. Forexample, these blends are useful as protective barrier films and may beused in disposable absorbent articles such as infant diapers,incontinence briefs, sanitary napkins, tampons, bed liners, bedpanliners, bandages, and the like. It is preferred that the films of theinvention have a tangent modulus of 2.5×10⁵ psi to 0.01×10⁵ psi, atensile strength of at least about 0.5×10³ psi, an average tear force ofat least about 7.0 g/mil, and an elongation at break of at least about5%. Also preferred is wherein said films have a thickness of about 0.1mil to about 20 mil and a water vapor transmission rate less than about500 g mil/m² -24 hours.

The blends and/or AAPEs of this invention can also be used in the otherparts of disposable diapers. In addition to being used as a protectivebarrier film, these blends and/or AAPEs can be used as tabs, nonwovens,fibers, tape, and other parts needed in the construction of a diaper.

We have found that films prepared from these binary and ternary blendsof cellulose esters as well as from AAPEs have desirable moisturebarrier properties. With the blends, the specific rates can be modifiedby modification of the blend composition. For example, the water vaportransmission rates can be controlled by the amount of aliphaticpolyester, aliphatic-aromatic copolyester, or polymeric compoundspresent in the binary or ternary blends. The water vapor transmissionrates can also be controlled by the amount of aromatic dicarboxylic acidmonomer present in the aliphatic-aromatic copolyester component of theblend. Of course, the water vapor transmission rates of the blends canbe additionally controlled by the addition of an immiscible hydrophobicagent.

The blends and/or AAPEs of this invention are also useful as moldedplastic parts or as solid, foamed plastic objects. Examples of suchparts include eyeglass frames, toothbrush handles, toys, automotivetrim, tool handles, camera parts, razor parts, ink pen barrels,disposable syringes, bottles, and the like. The plastic parts,especially those made by a foamed method which gives the plastic partincreased surface area, of this invention are particularly useful inapplications were it is desired that the plastic part be environmentallynon-persistent. Injection molding bars made from the blends and/or AAPEof the invention typically have a flexural modulus of 5.0×10⁵ psi to0.1×10⁵ psi, a flexural strength of 13×10³ psi to 0.1×10³ psi, and anotched Izod (23° C.) of 1.0 to 25 ft-lb/in. It is preferred that themolding bars have a flexural modulus of 3.8×10⁵ psi to 1.5×10⁵ psi, aflexural strength of 11.4×10³ psi to 4×10³ psi, and a notched Izod (23°C.) of 2 to 15 ft-lb/in.

The blends and/or AAPE of this invention are also useful as fibers.Examples of fiber applications include cigarette filters, diapertopsheet, sanitary napkins, fishing line, fishing nets, fiber forproducing surgical clothing, hygiene articles, absorbent fibers, fibersfor conveying liquids, and the like. We have found that, in addition tobeing spun from an appropriate solvent, the blends and/or AAPE of thisinvention can be melt-spun to produce fibers with excellent strength.The fibers can be oriented by drawing the fiber after spinning or byorientation during the spinning (cabinet orientation). Fibers producedfrom the blends and/or AAPEs have excellent shape retention even forfibers with complex cross-sectional shapes. We have also found that thefibers can be readily crimped. Fiber produced from the blends and/orAAPEs typically have a denier/filament (DPF) of 30-0.1. The preferreddenier is 10-1.5 DPF. For fluid management, the fiber can containhydrophobic agents or, optionally, can be coated with hydrophobicagents.

The blends, films, plastic objects, and fibers prepared from the blendsof the invention have a melt temperature between about 120° C. and about280° C. The preferred melt temperature range from 150° C. to 190° C.Also, such blends, films, plastic objects, and fibers have a glasstransition temperature (Tg) as measured by differential scanningcalorimetry (DSC) or dynamic mechanical thermal analysis (DMTA) of about25° C. to about 200° C. The preferred range for the glass transitiontemperatures is 50° C. to 100° C. The blends and films are alsopreferably non-tacky.

The preferred AAPE of this invention and products made therefrom havemelting points between 75° C. and 160° C. The more preferred range isbetween 80° C. and 140° C.

For the blends of the invention containing cellulose esters andaliphatic-aromatic copolyesters, the preferred level of polyester in theblend depends, in general, upon the desired level of miscibility of theblend and upon the needed physical properties. A preferred range is whencomponent I(B) is present in an amount of about 5% to about 75% andcomponent I(A) is present in an amount of about 25% to about 95% andthat component I(A) have a DS of 2.1-2.75. When it is desirable to havehigher tensile strength, flexural strength, and flexural modulus inmolded plastic objects and the like, a more preferred range is whencomponent I(B) is present in an amount of about 5% to about 25% and thatcomponent I(B) has an I.V. of 0.2-2.0 and component I(A) is present inan amount of about 75% to about 95% and that component I(A) have a DS of2.1-2.75. When it is desirable that the blend used for the moldedplastic part be miscible, that is optically clear, it is preferred thatcomponent I(B) have an I.V. of 0.3-0.6 and be present in the amount of5-25%.

When it is desirable to have lower modulus blends for applications suchas films, bottles, fiber, and the like, a more preferred range is whencomponent I(B) is present in an amount of about 30% to about 75% andcomponent I(A) is present in an amount of about 25% to about 70% andthat component I(A) have a DS of 2.1-2.75. When it is desirable to havea miscible blend useful in films, bottles, fiber, and the like, a morepreferred range is when component I(B) is present in an amount of about30% to about 55%, R⁵ is glutaric present in the 70-85% range, andcomponent I(A) is present in an amount of about 45% to about 70% andthat component I(A) have a DS of 2.5-2.75. The most preferred partiallymiscible blend useful in films is when component I(B) is present in anamount of about 60% to about 75%, R⁵ is glutaric present in the 45-60%range, and component I(A) is present in an amount of about 25% to about40% and that component I(A) have a DS of 2.5-2.75.

For the blends of the invention containing cellulose esters andaliphatic polyesters it is preferred that component II(B) is present inan amount of about 10% to about 60% and component II(A) is present in anamount of about 40% to about 90% and that component II(A) have a DS of2.1-2.7. Most preferred is when component II(B) is present in an amountof about 35% to about 55% and component II(A) is present in an amount ofabout 45% to about 65% and that component II(A) have a DS of 2.1-2.5.

For the blends of the invention containing cellulose esters and/oraliphatic polyesters and/or aliphatic-aromatic copolyesters and/orpolymeric compounds it is preferred that component III(B) is present inan amount of about 10% to about 50%, component III(A) is present in anamount of about 40% to about 88% and that component III(A) have a DS of2.1-2.75, and that component III(C) is present in the amount of 2% to10%. Also preferred is when component III(B) is present in an amount ofabout 2% to about 10%, component III(A) is present in an amount of about40% to about 88% and that component III(A) have a DS of 2.1-2.75, andthat component III(C) is present in the amount of 10% to 50%.Additionally preferred is when component III(B) is present in an amountof about 40% to about 88%, component III(A) is present in an amount ofabout 2% to about 10% and that component III(A) have a DS of 2.1-2.7,and that component III(C) is present in the amount of 10% to 50%. Alsopreferred is when component III(B) is present in an amount of about 10%to about 50%, component III(A) is present in an amount of about 2% toabout 10% and that component III(A) have a DS of 2.1-2.7, and thatcomponent III(C) is present in the amount of 40% to 88%. Anotherpreferred range is when component III(B) is present in an amount ofabout 20% to about 40%, component III(A) is present in an amount ofabout 20% to about 40% and that component III(A) have a DS of 2.1-2.7,and that component III(C) is present in the amount of 20% to 40%.

For the binary and ternary blends containing biodegradable additives itis preferred that component IV(B) is present in an amount of about 1% toabout 10% and component IV(A) is present in an amount of about 90% toabout 99%.

For the binary and ternary blends containing immiscible hydrophobicagents it is preferred that component V(B) is present in an amount ofabout 0.1% to about 1% and component V(A) is present in an amount ofabout 99% to about 99.9%.

Physical mixing of the components to form a blend can be accomplished ina number of ways such as mixing the components in the appropriatesolvent (e.g., acetone, THF, CH₂ Cl₂ /MeOH, CHCl₃, dioxane, DMF, DMSO,AcOMe, AcOEt, pyridine) followed by film casting or fiber extrusion. Theblend components can also be mixed by thermally compounding. The mostpreferred method is by thermally compounding in an apparatus such as atorque rheometer, a single screw extruder, or a twin screw extruder. Theblends produced by thermally compounding can be converted to thin filmsby a number of methods known to those skilled in the art. For example,thin films can be formed by dipcoating as described in U.S. Pat. No.4,372,311, by compression molding as described in U.S. Pat. No.4,427,614, by melt extrusion as described in U.S. Pat. No. 4,880,592, bymelt blowing, or by other similar methods. The blends can be convertedto molded plastic objects by injection molding as well as by extrusioninto a sheet from which an object is cut or stamped. The thermallycompounded blends can be used for melt extrusion of fiber as well.

The fibers and films prepared from the blends and/or the AAPE of thepresent invention are useful in applications where protective barrierfilms are desirable. For example, they may be used in absorbent articlessuch as infant diapers, incontinence briefs (adult diapers), sanitarynapkins, tampons, bed liners, bedpans, bandages, and the like. Thebiodegradable films, fibers, AAPE, and blends of the invention areparticularly useful in disposable articles because of environmentalconsiderations. The blends and/or films of the invention can also beused to make non-absorbent articles such as packaging materials (forexample, foam sheets for packaging), food bags, trash bags, agriculturalcompost sheets, film base for tape and photographic film, as well assolid plastic articles such as syringes and camera cases.

Biodegradable materials, such as the preferred barrier films of thisinvention, are materials that are comprised of components which, bymicrobial catalyzed degradation, are reduced in film or fiber strengthby reduction in polymer size to monomers or short chains which are thenassimilated by the microbes. In an aerobic environment, these monomersor short chains are ultimately oxidized to CO₂, H₂ O, and new cellbiomass. In an anaerobic environment the monomers or short chains areultimately oxidized to CO₂, H₂, acetate, methane, and cell biomass.Successful biodegradation requires that direct physical contact must beestablished between the biodegradable material and the active microbialpopulation or the enzymes produced by the active microbial population.An active microbial population useful for degrading the films and blendsof the invention can generally be obtained from any municipal orindustrial wastewater treatment facility in which the influents (wastestream) are high in cellulose materials. Moreover, successfulbiodegradation requires that certain minimal physical and chemicalrequirements be met such as suitable pH, temperature, oxygenconcentration, proper nutrients, and moisture level. We have found thatcertain cellulose esters are biodegradable in conventional wastewatertreatment facilities and in an in vitro enrichment system and hence areparticularly useful in the preparation of blends to be used for barrierfilms and fibers in disposable articles. We have also found that many ofthe blends and AAPE degrade in a composting environment and hence areuseful in the preparation of materials to be used as environmentallynonpersistent materials.

The following examples are to illustrate the invention but should not beinterpreted as a limitation thereon.

EXAMPLES

In the following examples, the blends were prepared by three generalmethods:

(i) the blend components are shaken together before compounding at theappropriate temperature in a Rheometrics Mechanical Spectrometer. Theresulting resin is typically ground to 5 mm particle size and a portionis pressed between two metal plates at a temperature above the melttemperature of the resin to form a melt pressed film;

(ii) blends of the cellulose esters and polyesters were prepared bycompounding on a 30 mm Werner-Pfleiderer twin screw extruder. Thetypical procedure is as follows: Two separate feed systems, one for thecellulosic and one for the polyester were utilized for this method ofmelt blending. The cellulose ester was added as a dry powder in Zone 1and the polyester was added as a viscous liquid in Zone 3. The celluloseester was added at the desired rate using an AccuRate feeder through ahopper into the barrel of the extruder. The polyester was pre-heatedunder nitrogen and was poured into a heated feed tank. The polyester wasmaintained under a nitrogen atmosphere and gravity fed through astainless steel line to a gear pump which transferred the moltenmaterial through a stainless steel line (1/2 inch outer diameter) intothe barrel of the extruder. All lines for this feed system were heatedand insulated. The production rate of the extruder is in the range of10-50 pounds/hr. The zone temperatures are set depending on the exactnature of the polyester and the cellulose ester and generally vary inthe range of about 100° C. to 250° C. Afterwards, the two strands ofmaterial exiting the extruder were quenched in water and chopped with aCONAIR JETRO pelletizer.

(iii) blends of the cellulose esters and polyesters were prepared bycompounding on a 30 mm Werner-Pfleiderer twin screw extruder. Thetypical procedure is as follows: A single feed system was utilized forthis method of melt blending. The cellulose ester and the polyester weredry blended and added as a solid in Zone 1. The dry blend was added atthe desired rate using an AccuRate feeder through a hopper into thebarrel of the extruder. The production rate of the extruder is in therange of 10-50 pounds/hr. The zone temperatures are set depending on theexact nature of the polyester and the cellulose ester and generally varyin the range of about 100° C. to 250° C. Afterwards, the two strands ofmaterial exiting the extruder were quenched in water and chopped with aCONAIR JETRO pelletizer.

The tensile strength, break to elongation, and tangent modulus of thefilms are measured by ASTM method D882; the tear force is measured byASTM method D1938; the oxygen and water vapor transmission rates aremeasured by ASTM methods D3985 and F372, respectively. The tensilestrength and elongation at break for molded pieces are measured by ASTMmethod D638; the flexural strength and modulus by ASTM method D790; theIzod impact strength by ASTM method D256; the heat deflectiontemperature by ASTM method D648. Inherent viscosities are measured at atemperature of 25° C. for a 0.5 gram sample in 100 ml of a 60/40 byweight solution of phenol/tetrachloroethane. Dynamic mechanical thermalanalysis (DMTA) spectra were collected using a Polymer Laboratories MkII at 4° C./min and 1 Hz.

Abbreviations used herein are as follows: "IV" is inherent viscosity;"g" is gram; "psi" is pounds per square inch; "cc" is cubic centimeter;"m" is meter; "rpm" is revolutions per minute; "DSPr" is degree ofsubstitution per anhydroglucose unit for propionyl; "DSAc" is degree ofsubstitution per anhydroglucose unit for acetyl; "DSBu" is degree ofsubstitution per anhydroglucose unit for butyryl; "BOD" is biochemicaloxygen demand; "vol." or "v" is volume; "wt." is weight; "mm" ismicrometer; "NaOAc" is sodium acetate; "nm" is not measured; "CE" iscellulose ester; "PE" is polyester; "DOA" is dioctyl adipate; "HDT" isheat deflection temperature; "WVTR" is water vapor transmission rate;"mil" is 0.001 inch. Relative to the clarity of the films, "+" indicatesa transparent film characteristic of a miscible blend; "±" indicates ahazy film characteristic of a partially miscible film; "-" indicates anopaque film characteristic of a immiscible blend; "AAPE" isaliphatic-aromatic copolyester and, as used herein, refers to thecopolyesters where blending is not required. Relative to naming of thecellulose ester, "CAP" is cellulose acetate propionate; "CA" iscellulose acetate; "CAB" is cellulose acetate butyrate. Relative tonaming of the polyester, representative examples are: "PTS(T) [85/15]"is poly(tetramethylene succinate-co-terephthalate) were the mole percent of succinate to terephthalate is 85/15; "PTA(T) [85/15]" ispoly(tetramethylene adipate-co-terephthalate) were the mole per cent ofadipate to terephthalate is 85/15; "PTG(T) [85/15]" ispoly(tetramethylene glutarate-co-terephthalate) were the mole per centof glutarate to terephthalate is 85/15; "PTG(T)(D) [60/35/5]" ispoly(tetramethylene glutarate-co-terephthalate-co-diglycolate) were themole per cent of glutarate to terephthalate to diglycolate is 60/35/5;"PTG(N) [85/15]" is poly(tetramethylene glutarate-co-naphthalate) werethe mole per cent of glutarate to naphthalate is 85/15; "PES" ispoly(ethylene succinate); "PHS" is poly(hexamethylene succinate); "PEG"is poly(ethylene glutarate); "PTG" is poly(tetramethylene glutarate);"PHG" is poly(hexamethylene glutarate); "PT(E)G [50/50]" ispoly(tetramethylene-co-ethylene glutarate) were the mole % oftetramethylene to ethylene is 50/50; "PEA" is poly(ethylene adipate);"PDEA" is poly(diethylene adipate); "PHA" is poly(hexamethyleneadipate). Other abbreviations are: "TEGDA" is triethylene glycoldiacetate; "PVA" is poly(vinyl acetate); "PMMA" is poly(methylmethacrylate); "PEMA" is poly(ethyl methacrylate). MYVAPLEX 600 is thetrade name for concentrated glyceryl monostearates and is available fromEastman Chemical Company. MYVAPLEX concentrated glyceryl monostearate isa 90% minimum distilled monoglyceride produced from hydrogenated soybeanoil which is composed primarily of stearic acid esters. MYVACET is thetrade name for distilled acetylated monoglycerides of modified fats. Theper cent acetylation of MYVACET 507 ranges from 48.5 to 51.5; the percent acetylation of MYVACET 707 ranges from 66.5 to 69.5; the per centacetylation of MYVACET 908 is a minimum of 96. MYVEROL is the trade namefor concentrated glyceryl monostearates and is available from EastmanChemical Company. MYVEROL is very similar to MYVAPLEX except that thedistilled monoglyceride is produced from different fat sources.

EXAMPLE 1

Blends of cellulose acetate propionate (DS_(Ac) =0.10, DS_(Pr) =2.64,IV=1.3) and aliphatic-aromatic copolyesters and films made from theblends were prepared using the standard procedures. Glass transitiontemperature were measured by DMTA and were calculated using theFox-Flory equation. The results are given in Tables I and II.

                  TABLE I                                                         ______________________________________                                        Tg, IV, and Clarity of CAP/Aliphatic-Aromatic                                 Copolyester Blends                                                                               Tg      Tg                                                                    (exp)   (cal)                                                                              IV   IV                                       Entry Polyester    °C.                                                                            °C.                                                                         PE   Blend Clarity                            ______________________________________                                        1     20% PTS(T)   124     110  1.0  1.1   +                                        [85/15]                                                                 2     40% PTS(T)    93      75  1.0  1.1   +                                        [85/15]                                                                 3     20% PTA(T)   125     110  0.7  1.0   +                                        [85/15]                                                                 4     40% PTA(T)    87      76  0.7  0.9   +                                        [85/15]                                                                 5     20% PEG(T)   139     110  0.6  0.9   +                                        [85/15]                                                                 6     40% PEG(T)    75      78  0.6  1.0   +                                        [85/15]                                                                 7     10% PEG(T)   146     143  0.9  1.0   +                                        [70/30]                                                                 8     20% PEG(T)   136     113  0.9  1.0   +                                        [70/30]                                                                 9     30% PEG(T)    126*    97  0.9  1.0   +                                        [70/30]                                                                 10    40% PEG(T)    82      83  0.6  1.0   +                                        [70/30]                                                                 11    55% PEG(T)    62      59  0.6  0.9   +                                        [70/30]                                                                 12    70% PEG(T)   25, 85,  34  0.9  0.9   +                                        [70/30]      98                                                         13    40% PTG(T)    93      66  1.2  nm    +                                        [95/5]                                                                  14    20% PTG(T)   127     105  0.9  nm    +                                        [90/10]                                                                 15    40% PTG(T)    88      65  0.9  1.0   +                                        [90/10]                                                                 16    40% PT(E)G(T)                                                                               71      72  0.7  1.0   +                                        [50/50, 85/15]                                                          17    20% PT(E)G(T)                                                                              125     110  0.7  1.0   +                                        [50/50, 70/30]                                                          18    40% PT(E)G(T)                                                                               76      77  0.7  1.0   +                                        [50/50, 70/30]                                                          19    40% PTG(T)    75      71  0.7  1.0   +                                        [85/15]                                                                 20    20% PTG(T)   135     110  0.7  1.0   +                                        [70/30]                                                                 21    40% PTG(T)    82      73  0.7  1.0   +                                        [70/30]                                                                 22    20% PTG(T)   143     113  1.5  1.1   +                                        [60/40]                                                                 23    40% PTG(T)    130*    78  1.5  1.2   +                                        [60/40]                                                                 24    60% PTG(T)   3, 76,   43  1.5  1.0   ±                                     [60/40]      112                                                        25    70% PTG(T)   2, 108   26  1.5  1.2   ±                                     [60/40]                                                                 26    80% PTG(T)    5       9   1.5  0.9   ±                                     [60/40]                                                                 27    20% PHG(T)   143     106  1.2  1.2   +                                        [80/20]                                                                 28    40% PHG(T)    105*    66  0.7  0.9   +                                        [80/20]                                                                 29    20% PEG(N)   138     111  0.8  1.0   +                                        [85/15]                                                                 30    40% PEG(N)    102*    77  0.8  0.9   +                                        [85/15]                                                                 ______________________________________                                         *Broad transitions with shoulders.                                       

                                      TABLE II                                    __________________________________________________________________________    Mechanical Properties, Tear Strength, and Water Vapor Transmission Rates      Of Cellulose Ester/Aliphatic-Aromatic Copolyester Blends                                         Elongation                                                                          Tangent                                                                            Tensile                                                                            Tear WVTR                                                     at Break                                                                            Modulus                                                                            Strength                                                                           Strength                                                                           (g mil/100)                           Sample                                                                            Polyester      (%)   (10.sup.5 psi)                                                                     (10.sup.3 psi)                                                                     (g/mil)                                                                            in.sup.2 -24 hours)                   __________________________________________________________________________    1   20% PTS(T) [85/15]                                                                           8     2.11 5.97 14.8 222                                   2   40% PTS(T) [85/15]                                                                           82    0.22 2.83 14.7 173                                   3   20% PTA(T) [85/15]                                                                           6     1.86 5.03 12.0 nm                                    4   40% PTA(T) [85/15]                                                                           61    0.19 1.62 10.3 nm                                    5   20% PEG(T) [85/15]                                                                           4     2.21 6.11 8.0  nm                                    6   40% PEG(T) [85/15]                                                                           91    0.31 2.89 14.4 253                                   7   10% PEG(T) [70/30]                                                                           3     2.21 4.90 10.0 172                                   8   20% PEG(T) [70/30]                                                                           4     2.21 6.29 7.5  216                                   9   30% PEG(T) [70/30]                                                                           18    1.35 4.24 11.5 184                                   10  40% PEG(T) [70/30]                                                                           47    0.59 2.83 10.9 145                                   11  55% PEG(T) [70/30]                                                                           54    0.06 1.16 12.6 272                                   12  70% PEG(T) [70/30]                                                                           114   0.02 0.42 25.8 nm                                    13  40% PTG(T) [95/5]                                                                            75    0.10 1.70 9.3  nm                                    14  20% PTG(T) [90/10]                                                                           21    1.78 5.33 11.4 nm                                    15  40% PTG(T) [90/10]                                                                           77    0.12 2.02 9.9  nm                                    16  40% PT(E)G(T) [50/50, 85/15]                                                                 81    0.27 2.58 14.1 216                                   17  20% PT(E)G(T) [50/50, 70/30]                                                                 3     2.15 5.58 7.2  nm                                    18  40% PT(E)G(T) [50/50, 70/30]                                                                 61    0.43 2.81 13.7 175                                   19  40% PTG(T) [85/15]                                                                           83    0.24 2.48 11.5 246                                   20  20% PTG(T) [70/30]                                                                           5     1.23 6.26 12.4 188                                   21  40% PTG(T) [70/30]                                                                           50    0.37 2.05 16.3 238                                   22  20% PTG(T) [60/40]                                                                           8     1.13 3.47 20.2 364                                   23  40% PTG(T) [60/40]                                                                           82    0.99 4.01 23.6 275                                   24  60% PTG(T) [60/40]                                                                           72    0.28 1.89 14.9 nm                                    25  70% PTG(T) [60/40]                                                                           63    0.21 1.32 19.1 nm                                    26  80% PTG(T) [60/40]                                                                           207   0.09 1.11 59.2 nm                                    27  20% PHG(T) [80/20]                                                                           30    1.5  4.87 4.6  nm                                    28  40% PHG(T) [80/20]                                                                           45    0.25 1.35 10.5 nm                                    29  20% PEG(N) [85/15]                                                                           12    2.14 6.05 11.1 175                                   30  40% PEG(N) [85/15]                                                                           69    0.38 2.66 14.4 308                                   __________________________________________________________________________

The IV data from Table I illustrates that the molecular weight of theblend components are preserved in the blending process. As the clarityindicates, the films were transparent which is characteristic ofmiscible blends.

Table I demonstrates that each of the blends involving 20%aliphatic-aromatic copolyester (entries 1, 3, 5, 8, 14, 17, 20, 22, 27,and 29) had an experimental Tg₁₂ which was 14° to 37° C. higher than theTg₁₂ calculated for each blend. The 40% aliphatic-aromatic copolyesterblends involving a C4 diacid (entry 2), a C6 diacid (entry 4), or a C10aromatic diacid (entry 30) also showed a 18°, 11°, and 25° C.,respectively, positive deviation of the experimental Tg₁₂ from thetheoretical Tg₁₂. Within the family of 40% aliphatic-aromaticcopolyester involving a C5 aliphatic diacid, the experimental Tg₁₂ ofentries 6, 10, 16, 19, and 21 (15-30% C6 aromatic diacid) showed goodagreement with the theoretical Tg₁₂ (±10° C.). In contrast, theexperimental Tg₁₂ 's of the 40% PTG(T) blends containing 5, 10, and 40%C6 aromatic diacid showed a 27°, 23°, and 52° C., respectively, positivedeviation from the calculated value. In the series of 10-70% PEG(T)[70/30] (entries 7-12), the 10-30% blends showed a positive deviation ofthe experimental T₁₂ from the calculated values, the 40-55% blends hadTg₁₂ 's which showed excellent agreement with the calculated Tg₁₂ 's,and the 70% blend showed multiple Tg's characteristic of a partiallymiscible blend. In contrast, the series of 20-70% PTG(T) [60/40] blends(entries 22-25) either had multiple Tg₁₂ 's or Tg₁₂ 's that were quitedifferent from theoretical. At very high levels of aliphatic-aromaticcopolyester (cf. entry 26), single Tg's were observed. Analysis of thistype suggests that blends of cellulose esters with aliphatic-aromaticcopolyester involving a C5 aliphatic diacid are generally miscible inapproximately the 30-55% range when the aromatic portion of thecopolyesters is approximately 15-30%. Aliphatic-aromatic copolyesterblends involving a C5 aliphatic diacid outside of the 30-55% rangeexhibit varying levels of miscibilities. Blends involving otheraliphatic diacids also exhibit varying levels of miscibilities through awider range.

Blend miscibility is also strongly dependent upon the molecular weightof the polyester. In general, a low I.V. polyester will give a widerwindow of miscibility.

Cellulose esters typically have high WVTR (>500 g mil/100 in² -24 h). AsTable II shows, all of the CAP/aliphatic-aromatic copolyester blendshave WVTR less than 500 g mil/100 in² -24 h. Table II also demonstratesthat a wide range of physical properties for materials prepared from theblends are possible depending upon the blend components and blendcomposition. Many of the aliphatic-aromatic copolyester blends gaveunexpected and unusual physical properties. For example, the tangentmodulus (Table II) for the 20% blends were, for the most part,surprisingly high relative to the CAP (2.1×10⁵ psi). With the exceptionof the blends involving PTG(T) [70/30] and PTG(T) [60/40], the tangentmoduli all remained above 1.5×10⁵ psi. Even more surprising was thetensile strength for the 20% blends. With the exception of the PTG(T)[60/40] blend, the tensile strength of these blends were all above5.0×10³ psi; in some cases the tensile strength was improved relative tothe CAP (5.5×10³). In general, with the exception of the PTG(T) [60/40]blends, all of the blends involving 20% aliphatic-aromatic copolyesterbehaved very similar to the blend major component, cellulose acetatepropionate. In effect, we were able to substitute 20% of a copolyester,which generally has much different physical properties than thecellulose ester blend component, for cellulose ester without lowering,and in some case improving, the mechanical properties inherent to thecellulose acetate propionate.

EXAMPLE 2

Blends of cellulose esters and succinate polyesters and films therefromwere prepared using the standard procedures. The results are given inTables III and IV.

                  TABLE III                                                       ______________________________________                                        DS/AGU, IV, and Clarity of Cellulose                                          Ester/Polyester Blends: C4 Diacids                                            En-                             IV   IV   IV    Clar-                         try  Polyester .sup.Ds Ac                                                                           Ds.sub.Pr                                                                          DS.sub.Bu                                                                          CE   PE   Blend ity                           ______________________________________                                        31   10% PES   2.50   --   --   1.2  1.0  1.25  +                             32   20% PES   2.50   --   --   1.2  1.0  1.18  +                             33   20% PES   0.10   2.64 --   1.3  1.1  1.18  +                             34   40% PES   0.10   2.64 --   1.3  1.0  1.11  +                             35   20% PHS   0.10   2.64 --   1.3  1.0  1.16  +                             36   40% PHS   0.10   2.64 --   1.3  1.0  1.11  +                             ______________________________________                                    

                  TABLE IV                                                        ______________________________________                                        Mechanical Properties and Tear Strength Of Films Prepared                     From Cellulose Ester/Polyester Blends: C4 Diacids                                             Elongation                                                                              Tangent                                                                              Tensile                                                                              Tear                                                  at Break  Modulus                                                                              Strength                                                                             Strength                              Entry Polyester (%)       (10.sup.5 psi)                                                                       (10.sup.3 psi)                                                                       (g/mil)                               ______________________________________                                        31    10% PES   nm        nm     nm     nm                                    32    20% PES   nm        nm     nm     nm                                    33    20% PES   11        1.92   5.45   nm                                    34    40% PES   48        0.71   2.97   nm                                    35    20% PHS   36        1.70   4.68   nm                                    36    40% PHS   87        0.26   2.32   12.2                                  ______________________________________                                    

The IV data from Table III illustrates that the molecular weight of theblend components are preserved in the blending process. As the clarityindicates, the films were transparent which is characteristic ofmiscible blends. Furthermore, the Tg of the blend was measured forrepresentative samples. Entries 34 and 36 had a single Tg of 80° C. and70° C., respectively. A single Tg is also characteristic of miscibleblends. As Table IV demonstrates, a very wide range of physicalproperties for materials prepared from the blends are possible by properselection of the blend composition.

EXAMPLE 3

Blends of cellulose esters and glutarate polyesters and films therefromwere prepared using the standard procedures. The results are given inTables V and VI.

                  TABLE V                                                         ______________________________________                                        DS/AGU, IV, and Clarity of Cellulose                                          Ester/Polyester Blends: C5 Diacids                                            En-                             IV   IV   IV    Clar-                         try  Polyester Ds.sub.Ac                                                                            Ds.sub.Pr                                                                          DS.sub.Bu                                                                          CE   PE   Blend ity                           ______________________________________                                        37   50% PEG   2.50   --   --   1.2  --   nm    +                             38   20% PEG   0.10   2.64 --   1.3  1.2  1.21  +                             39   40% PEG   0.10   2.64 --   1.3  1.2  1.19  +                             40   35% PEG   0.34   2.15 --   1.6  0.9  nm    +                             41   40% PEG   0.34   2.15 --   1.6  0.9  nm    +                             42   45% PEG   0.34   2.15 --   1.6  0.9  nm    +                             43   35% PEG   0.12   2.14 --   1.3  1.1  nm    +                             44   40% PEG   0.12   2.14 --   1.3  0.9  nm    +                             45   35% PEG   0.11   2.05 --   1.6  0.9  nm    +                             46   40% PEG   0.11   2.05 --   1.6  0.9  nm    +                             47   45% PEG   0.11   2.05 --   1.6  0.9  nm    +                             48   20%       0.10   2.64 --   1.3  1.1  1.21  +                                  PDEG                                                                     49   40%       0.10   2.64 --   1.3  1.1  nm    +                                  PDEG                                                                     50   40%       0.10   2.64 --   1.3  0.7  nm    +                                  PT(E)G                                                                        [50,50]                                                                  51   10% PTG   0.10   2.64 --   1.3  0.5  1.20  +                             52   20% PTG   0.10   2.64 --   1.3  0.5  1.21  +                             53   30% PTG   0.10   2.64 --   1.3  0.6  1.07  +                             54   35% PTG   0.10   2.64 --   1.3  0.5  1.07  +                             55   40% PTG   0.10   2.64 --   1.3  0.5  1.11  +                             56   40% PTG   0.10   2.64 --   1.3  0.6  1.06  +                             57   40% PTG   0.10   2.64 --   1.3  1.1  nm    +                             58   20% PTG   0.10   2.64 --   1.3  1.7  1.25  +                             59   25% PTG   0.10   2.64 --   1.3  1.7  1.27  +                             60   30% PTG   0.10   2.64 --   1.3  1.7  1.25  +                             61   35% PTG   0.10   2.64 --   1.3  1.7  1.25  +                             62   40% PTG   0.10   2.64 --   1.3  1.7  1.31  +                             63   50% PTG   0.10   2.64 --   1.3  1.7  1.30  +                             64   40% PTG   0.17   2.29 --   1.7  1.1  nm    +                             65   40% PTG   0.04   2.28 --   1.6  1.7  nm    +                             66   40% PTG   0.34   2.15 --   1.6  1.1  nm    +                             67   35% PTG   0.34   2.15 --   1.6  1.1  nm    +                             68   40% PTG   0.10   2.16 --   1.0  1.1  nm    +                             69   40% PTG   0.12   2.14 --   1.3  1.1  nm    +                             70   35% PTG   0.11   2.05 --   1.6  1.1  nm    +                             71   40% PTG   0.11   2.05 --   1.6  1.1  nm    +                             72   45% PTG   0.11   2.05 --   1.6  1.1  nm    +                             73   30% PHG   0.10   2.64 --   1.3  0.5  1.06  +                             74   40% PHG   0.10   2.64 --   1.3  0.5  0.99  +                             75   35% PTG   1.01   --   1.67 1.2  --   nm    +                             76   40% PTG   2.04   --   0.70 1.2  --   nm    +                             ______________________________________                                    

                  TABLE VI                                                        ______________________________________                                        Mechanical Properties and Tear Strength for Films Prepared                    From Cellulose Ester/Aliphatic Polyester Blends: C5 Diacids                                    Elonga-                                                                       tion     Tangent                                                                              Tensile                                                                              Tear                                                   at Break Modulus                                                                              Strength                                                                             Strength                              Entry Polyester  (%)      (10.sup.5 psi)                                                                       (10.sup.3 psi)                                                                       (g/mil)                               ______________________________________                                        37    50% PEG    nm       nm     nm     nm                                    38    20% PEG    30       1.60   4.79   nm                                    39    40% PEG    95       0.24   2.49   13.3                                  40    35% PEG    80       0.52   3.44   18.5                                  41    40% PEG    84       0.33   2.78   10.0                                  42    45% PEG    104      0.21   2.56   15.9                                  43    35% PEG    33       0.38   1.80   12.6                                  44    40% PEG    19       0.24   1.07    9.8                                  45    35% PEG    51       0.48   3.04   13.3                                  46    40% PEG    86       0.32   2.80   10.4                                  47    45% PEG    77       0.20   1.61   12.7                                  48    20% PDEG   24       1.41   3.54    5.1                                  49    40% PDEG   60       0.14   1.08   19.8                                  50    40% PT(E)G 76       0.15   1.73    9.1                                        [50,50]                                                                 51    10% PTG    30       1.70   5.49   12.7                                  52    20% PTG    43       1.20   3.72   nm                                    53    30% PTG    65       0.73   2.97   16.7                                  54    35% PTG    88       0.25   2.54   14.9                                  55    40% PTG    53       0.15   1.18   11.8                                  56    40% PTG    61       0.13   1.26   12.4                                  57    40% PTG    71       0.12   1.59   13.3                                  58    20% PTG    18       1.68   4.64   12.5                                  59    25% PTG    67       1.27   4.41   18.7                                  60    30% PTG    69       0.96   3.31   21.5                                  61    35% PTG    72       0.45   2.36   22.9                                  62    40% PTG    128      0.13   2.68   18.0                                  63    50% PTG    117      0.05   2.14   23.0                                  64    40% PTG    113      0.22   2.67   15.8                                  65    40% PTG    42       0.21   1.29   nm                                    66    40% PTG    97       0.27   2.50   19.9                                  67    35% PTG    92       0.59   3.94   19.8                                  68    40% PTG    37       0.16   1.09   12.2                                  69    40% PTG    36       0.22   1.27   15.4                                  70    35% PTG    54       0.43   2.45   12.8                                  71    40% PTG    53       0.26   1.97   12.9                                  72    45% PTG    47       0.19   1.32    9.3                                  73    30% PHG    57       0.68   2.43   17.4                                  74    40% PHG    60       0.16   1.23   12.4                                  75    35% PTG    93       0.32   2.99   12.4                                  76    40% PTG    27       0.86   0.35   12.6                                  ______________________________________                                    

The IV data from Table V illustrate that the molecular weight of theblend components are preserved in the blending process. As the clarityindicates, the films were transparent which is characteristic ofmiscible blends. Furthermore, the Tg of the blend was measured forrepresentative samples. Entries 37, 49, 51, 54, 55, 59, and 74 had asingle Tg of 120°, 70°, 125°, 72°, 66°, 108°, and 70° C., respectively.A single Tg is also characteristic of miscible blends. As Table VIdemonstrates, a very wide range of physical properties for materialsprepared from the blends are possible by proper selection of the blendcomposition.

EXAMPLE 4

Blends of cellulose esters and adipate polyesters and films therefromwere prepared using the standard procedures. The results are given inTables VII and VIII.

                  TABLE VII                                                       ______________________________________                                        DS/AGU, IV, And Clarity of Cellulose Ester/Aliphatic                          Polyester Blends: C6 Diacids                                                  En-                             IV   IV   IV    Clar-                         try  Polyester DS.sub.Ac                                                                            DS.sub.Pr                                                                          DS.sub.Bu                                                                          CE   PE   Blend ity                           ______________________________________                                        77   20% PEA   0.10   2.64 --   1.3  0.6  1.16  +                             78   25% PEA   0.10   2.64 --   1.3  0.6  1.11  +                             79   30% PEA   0.10   2.64 --   1.3  0.6  1.08  +                             80   35% PEA   0.10   2.64 --   1.3  0.6  1.04  +                             81   40% PEA   0.10   2.64 --   1.3  0.6  1.00  +                             82   45% PEA   0.10   2.64 --   1.3  0.6  0.96  +                             83   50% PEA   0.10   2.64 --   1.3  0.6  0.92  +                             84   20%       0.10   2.64 --   1.3  0.7  1.15  +                                  PDEA                                                                     85   40%       0.10   2.64 --   1.3  0.7  1.11  +                                  PDEA                                                                     86   20% PHA   0.10   2.64 --   1.3  0.7  1.17  +                             87   40% PHA   0.10   2.64 --   1.3  0.5  1.05  +                             ______________________________________                                    

                  TABLE VIII                                                      ______________________________________                                        Mechanical Properties and Tear Properties of Films Prepared                   From Cellulose Ester/Polyester Blends: C6 Diacids                                              Elonga-                                                                       tion     Tangent                                                                              Tensile                                                                              Tear                                                   at Break Modulus                                                                              Strength                                                                             Strength                              Entry Polyester  (%)      (10.sup.5 psi)                                                                       (10.sup.3 psi)                                                                       (g/mil)                               ______________________________________                                        77    20% PEA    13       1.39   3.95   4.1                                   78    25% PEA    43       0.99   3.37   14.1                                  79    30% PEA    74       0.57   2.76   16.6                                  80    35% PEA    90       0.32   2.44   12.6                                  81    40% PEA    75       0.14   1.37   13.0                                  82    45% PEA    62       0.06   1.20   4.1                                   83    50% PEA    75       0.03   1.03   4.7                                   84    20%        24       1.46   4.05   6.0                                         PDEA                                                                    85    40%        64       0.12   1.11   13.3                                        PDEA                                                                    86    20% PHA    18       1.30   3.60   15.2                                  87    40% PHA    81       0.14   1.36   13.6                                  ______________________________________                                    

The IV data from Table VII illustrate that the molecular weight of theblend components are preserved in the blending process. As the clarityindicates, the films were transparent which is characteristic ofmiscible blends. Furthermore, the Tg of the blend was measured forrepresentative samples. Entries 80 and 84 had a single Tg of 78° and130° C., respectively. A single Tg is also characteristic of miscibleblends. As Table VIII demonstrates, a very wide range of physicalproperties for materials prepared from the blends are possible by properselection of the blend composition.

EXAMPLE 5

Blends of cellulose esters and aliphatic polyesters containing differentadditives and films therefrom were prepared using the standardprocedures. The film of entries 96-101, 104, and 105 are blown filmwhere T means transverse direction and M means machine direction. Theresults are given in Tables IX and X.

                  TABLE IX                                                        ______________________________________                                        DS/AGU, IV, Clarity of Cellulose Ester/Aliphatic                              Polyester Blends Containing Representative Additives                          En-                                 IV   IV   Clar-                           try  Polyester/Additive                                                                          DS.sub.Ac                                                                            DS.sub.Pr                                                                          DS.sub.Bu                                                                          CE   PE   ity                             ______________________________________                                        88   39.9% PTG     0.10   2.64 --   1.3  1.1  +                                    0.1% Iron Stearate                                                       89   39.9% PTG     0.10   2.64 --   1.3  1.1  +                                    0.1% Zinc Stearate                                                       90   39.9% PTG     0.10   2.64 --   1.3  1.1  +                                    0.1% Mg Octanoate                                                        91   39.9% PTG     0.10   2.64 --   1.3  1.1  +                                    0.1% CaCO.sub.3                                                          92   39% PTG       0.10   2.64 --   1.3  1.1  +                                    1% CaCO.sub.3                                                            93   37.5% PTG     0.10   2.64 --   1.3  1.1  1                                    2.5% CaCO.sub.3                                                          94   39.75% PTG    0.10   2.64 --   1.3  1.1  +                                    0.25% Zeolite                                                            95   39% PTG       0.10   2.64 --   1.3  1.1  +                                    1% Zeolite                                                               96   40% PTG.sup.M 0.10   2.64 --   1.3  1.1  +                                    1% Microcrystalline                                                           Cellulose                                                                97   40% PTG.sup.T 0.10   2.64 --   1.3  1.1  +                                    1% Microcrystalline                                                           Cellulose                                                                98   40% PTG.sup.M 0.10   2.64 --   1.3  1.1  +                                    2% Microcrystalline                                                           Cellulose                                                                99   40% PTG.sup.T 0.10   2.64 --   1.3  1.1  +                                    2% Microcrystalline                                                           Cellulose                                                                100  40% PTG.sup.M 0.10   2.64 --   1.3  1.1  1                                    1% Microcrystalline                                                           Cellulose,                                                                    1% Silica, 1% TiO.sub.2                                                  101  40% PTG.sup.T 0.10   2.64 --   1.3  1.1  1                                    1% Microcrystalline                                                           Cellulose,                                                                    1% Silica, 1% TiO.sub.2                                                  102  20% PTG       0.10   2. 64                                                                              --   1.3  1.7  +                                    10% TEGDA                                                                103  40% PTG       0.10   2.64 --   1.3  1.1  +                                    2.5% Cellulose                                                                Monoacetate,                                                                  0.5% MYVAPLEX                                                                 600                                                                      104  41% PTG.sup.M 0.10   2.64 --   1.0  nm   1                                    0.5% PBT dye,                                                                 2% TiO.sub.2,                                                                 1% MYVAPLEX                                                                   600                                                                      105  41% PTG.sup.T 0.10   2.64 --   1.0  nm   1                                    0.5% PBT dye,                                                                 2% TiO.sub.2,                                                                 1% MYVAPLEX                                                                   600                                                                      ______________________________________                                         .sup.1 Films were opaque or colored due to the additive.                 

                  TABLE X                                                         ______________________________________                                        Mechanical Properties and Tear Strength of Films Prepared                     From cellulose Ester/Polyester Blends Containing                              Representative Additives                                                                        Elon-                                                                         gation                                                                        at      Tangent                                                                              Tensile                                                                              Tear                                  En-  Polyester/   Break   Modulus                                                                              strength                                                                             Strength                              try  Additive     (%)     (10.sup.5)                                                                           (10.sup.3)                                                                           (g/mil)                               ______________________________________                                        88   39.9% PTG    83      0.18   2.22   10.8                                       0.1% Iron                                                                     Stearate                                                                 89   39.9% PTG    68      0.14   1.70   11.1                                       0.1% Zinc                                                                     Stearate                                                                 90   39.9% PTG    74      0.14   1.97   11.5                                       0.1% Mg                                                                       Octanoate                                                                91   39.9% PTG    56      0.12   1.42   12.7                                       0.1% CaCO.sub.3                                                          92   39% PTG      51      0.11   1.17   13.2                                       1% CaCO.sub.3                                                            93   37.5% PTG    52      0.19   1.38   14.2                                       2.5% CaCO.sub.3                                                          94   39.75% PTG   64      0.08   1.67   12.8                                       0.25% Zeolite                                                            95   39% PTG      52      0.13   1.27   12.4                                       1% Zeolite                                                               96   40% PTG.sup.M                                                                              67      0.27   2.46   7.0                                        1% Microcrystal-                                                              line Cellulose                                                           97   40% PTG.sup.T                                                                              36      0.30   1.09   6.8                                        1% Microcrystal-                                                              line Cellulose                                                           98   40% PTG.sup.M                                                                              43      0.22   1.56   7.1                                        2% Microcrystal-                                                              line Cellulose                                                           99   40% PTG.sup.M                                                                              59      0.27   1.89   6.8                                        1% Microcrystal-                                                              line Cellulose                                                           100  40% PTG.sup.M                                                                              65      0.37   2.11   7.9                                        1% Microcrystal-                                                              line Cellulose,                                                               1% Silica,                                                                    1% TiO.sub.2                                                             101  40% PTG.sup.T                                                                              48      0.24   1.76   8.3                                        1% Microcrystal-                                                              line Cellulose,                                                               1% Silica,                                                                    1% TiO.sub.2                                                             102  10% PTG      79      0.42   1.87   12.7                                       10% TEGDA                                                                103  40% PTG      56      0.14   1.06   13.7                                       2.5% Cellulose                                                                Monoacetate,                                                                  0.5%                                                                          MYVAPLEX                                                                      600                                                                      104  41% PTG.sup.M                                                                              80      0.17   3.40   10.0                                       0.5% PTT dye,                                                                 2% TiO.sub.2,                                                                 1% MYVAPLEX                                                                   600                                                                      105  41% PTG.sup.T                                                                              68      0.30   4.48   7.5                                        0.5% PTT dye,                                                                 2% TiO.sub.2,                                                                 1% MYVAPLEX                                                                   600                                                                      ______________________________________                                    

As Table IX demonstrates, the blends of this invention can contain manydifferent types of additives ranging from pro-oxidants (cf. entries88-90), inorganics (cf. entries 91-95, 104,105), organic additives whichare highly biodegradable (cf. 96-101, 103), polymer dyes and pigments(cf. 104 or 105), to monomeric plasticizers (cf.102) among others.Entries 88-90, 102 were transparent while entries 91-99, 103 weretransparent but, as expected, hazy due to the inorganics or organicsadded to the blend. Entries 99 and 100 were white because of the TiO₂while 104 and 105 were blue because of the TiO₂ and dye; these examplesshow that the blends can be readily pigmented or dyed. As can be seenfrom Table X, these additives have little or no effect on the mechanicalproperties or tear strength of films prepared from the blends (cf.Tables X and VI). Hence, additives e.g., CaCO₃ or microcrystallinecellulose which promote biodegradation can be added to the blends whilemaintaining a wide range of physical properties for materials preparedfrom the blends by proper selection of the blend composition.

EXAMPLE 6

Ternary blends of cellulose acetate propionate with a DS/AGU of 2.74,aliphatic polyesters, and a third polymer component were prepared usingthe standard procedures. Table XI gives the mechanical properties, tearstrength, and clarity of the films made from the blends.

                                      TABLE XI                                    __________________________________________________________________________    Mechanical Properties, Tear Strength, and Clarity of Films Prepared           From CAP (DS/AGU = 2.75)/Aliphatic Polyester or Aliphatic-Aromatic            Copolyester/Polymer Ternary Blends                                                                   Elongation                                                                          Tangent                                                                            Tensile                                                                            Tear                                                          at Break                                                                            Modulus                                                                            Strength                                                                           Strength                               Entry                                                                             Polyester/Polymer  (%)   (10.sup.5)                                                                         (10.sup.3)                                                                         (g/mil)                                                                            Clarity                           __________________________________________________________________________    106 40% PTG            29    0.09 0.70 13.6 -                                     2% Polyvinyl Alcohol                                                          (100% hydrolyzed, MW = 115,000)                                               0.5% Myvaplex 600                                                         107 40% PTG            31    0.05 0.60 14.4 -                                     5% Polyvinyl Alcohol                                                          (100% hydrolyzed, MW = 115,000)                                               0.5% Myvaplex 600                                                         108 40% PTG            68    0.05 1.28 11.3 -                                     5% Polyvinyl Alcohol                                                          (98-99% Hydrolyzed,                                                           MW = 31,000-50,000)                                                           0.5% Myvaplex 600                                                         109 40% PTG            35    0.14 0.67 12.2 -                                     2% Polyvinyl Alcohol                                                          (87-89% hydrolyzed,                                                           MW = 124-186K)                                                                0.5% Myvaplex 600                                                         110 40% PTG            37    0.10 0.70 14.4 -                                     5% Polyvinyl Alcohol                                                          (87-89% hydrolyzed,                                                           MW = 124-186K)                                                                0.5% Myvaplex 600                                                         111 40% PTG            67    0.11 1.32 11.9 -                                     5% Polyvinyl Alcohol                                                          (87-89% hydrolyzed,                                                           MW - 31,000-50,000)                                                           0.5% Myvaplex 600                                                         112 40% PTG            93    0.08 1.93 10.1 +                                     5% Polyvinyl Alcohol                                                          (80% Hydrolyzed                                                               MW = 9,000-10,000)                                                        113 38% PTG            49    0.06 0.65 12.7 ±                                  2% ECDEL 9810                                                             114 35% PTG            74    0.32 2.11 15.0 -                                     5% Nylon 6                                                                115 37.5% PTG          92    0.09 1.09 13.7 ±                                  2.5% Nylon                                                                116 40% PTG            72    0.17 1.38 15.0 +                                     2% PVA, 0.5% MYVAPLEX 600                                                 117 40% PTG            93    0.11 1.56 18.3 +                                     5% PVA, 0.5% MYVAPLEX 600                                                 118 40% PTG            88    0.10 1.55 14.4 ±                                  10% PVA                                                                   119 28% PEG            306   0.05 1.28 NT   ±                                  52% PVA                                                                   120 31% PEG            509   0.02 1.06 NT   ±                                  59% PVA                                                                   121 40% PTG            86    0.12 1.45 17.4 +                                     5% PMMA, 0.5% MYVAPLEX 600                                                122 40% PTG            61    0.17 1.15 12.4 +                                     2% PMMA, 0.5% MYVAPLEX 600                                                123 40% PTG            75    0.10 1.48 11.3 +                                     10% PMMA                                                                  124 40% PTG            48    0.17 0.93 16.2 +                                     5% PEMA, 0.5% MYVAPLEX 600                                                125 40% PTG            71    0.19 1.23 13.2 +                                     2% PEMA, 0.5% MYVAPLEX 600                                                126 40% PTG            57    0.10 0.94 13.9 +                                     10% PEMA                                                                  127 35% PTG            70    0.20 1.80 20.3 +                                     5% Hydroxypropyl Cellulose                                                    (MW = 100,000)                                                            128 39% PTG            80    0.15 1.71 21.2 +                                     1% Hydroxypropyl Cellulose                                                    (MW = 1,000,000)                                                          129 35% PTG            80    0.22 1.74 16.9 +                                     5% Hydroxypropyl Cellulose                                                    (MW = 1,000,000)                                                          130 40% PTG            81    0.02 0.60 11.1 +                                     2% Ethylene/Vinyl Acetate                                                     Copolymer (40% vinyl acetate)                                             131 35% PTG            59    0.29 1.92 11.5 +                                     2% Ethylene/Vinyl Acetate Copolymer                                           (40% vinyl acetate)                                                       132 35% PTG            43    0.20 1.40 10.9 +                                     5% Ethylene/Vinyl Acetate                                                     Copolymer (40% vinyl acetate)                                             133 35% PTG            44    0.08 0.98 8.8  ±                                  10% Ethylene/Vinyl Acetate                                                    Copolymer (40% vinyl acetate)                                             134 35% PTG            35    0.46 1.09 8.0  +                                     2% Ethylene/Vinyl Acetate                                                     Copolymer (50% vinyl acetate)                                             135 35% PTG            35    0.13 1.03 8.7  +                                     5% Ethylene/Vinyl Acetate                                                     Copolymer (50% vinyl acetate)                                             136 35% PTG            28    0.05 0.80 10.4 ±                                  10% Ethylene/Vinyl Acetate                                                    Copolymer (50% vinyl acetate)                                             137 35% PTG            68    0.28 1.93 13.3 +                                     2% Ethylene/Vinyl Acetate                                                     Copolymer (70% vinyl acetate)                                             138 35% PTG            67    0.24 1.86 14.5 +                                     5% Ethylene/Vinyl Acetate                                                     Copolymer (70% vinyl acetate)                                             139 35% PTG            79    0.17 1.67 12.5 ±                                  10% Ethylene/Vinyl Acetate                                                    Copolymer (70% vinyl acetate)                                             140 40% PTG            75    0.07 1.40 nm   -                                     2% Lexan Polycarbonate                                                    141 40% PTG            70    0.08 1.28 nm   -                                     5% Lexan Polycarbonate                                                    142 40% PTG            65    0.04 1.15 nm   -                                     10% Lexan Polycarbonate                                                   __________________________________________________________________________

As Table XI shows, cellulose esters and aliphatic polyesters oraliphatic-aromatic copolyesters can be blended with other polymers toform either miscible or partially miscible ternary blends which haveexcellent physical properties. Entries 112, 116, 117, 119-130, 132, 133,135, and 136 are examples of miscible ternary blends while the remainingexamples are ternary blends which are partially miscible. These blendscan, of course, contain immiscible additives demonstrated in Example 5or in Example 7 (vide infra).

EXAMPLE 7

Ternary blends of cellulose esters and aliphatic polyesters oraliphatic-aromatic copolyester, and a hydrophobic additive were preparedusing the standard procedures. Tables XII and XIII gives the DS/AGU, IV,and clarity of the blends as well as the mechanical properties, tearstrength, and water vapor transmission rates of the films made from theblends.

                                      TABLE XII                                   __________________________________________________________________________    DS/AGU, IV, and Clarity of Cellulose Ester/Polyester Blends                   Containing Hydrophobic Additives                                                  Polyester/Hydrophobic                                                                              IV IV IV                                             Entry                                                                             Additive    DS.sub.Ac                                                                        DS.sub.Pr                                                                        DS.sub.Bu                                                                        CE PE Blend                                                                             Clarity                                    __________________________________________________________________________    143 39.95% PTG  0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              nm  +                                              0.05% MYVAPLEX 600                                                        144 39.9% PTG   0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              nm  +                                              0.1% MYVAPLEX 600                                                         145 39.75% PTG  0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              nm  +                                              0.25% MYVAPLEX 600                                                        146 39.5% PTG   0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              nm  +                                              0.5% MYVAPLEX 600                                                         147 39.25% PTG  0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              nm  +                                              0.75% MYVAPLEX 600                                                        148 39% PTG     0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              1.19                                                                              +                                              1% MYVAPLEX 600                                                           149 38.5% PTG   0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              1.22                                                                              +                                              1.5% MYVAPLEX 600                                                         150 38% PTG     0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              1.18                                                                              +                                              2% MYVAPLEX 600                                                           151 39% PTG     0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              1.23                                                                              +                                              1% MYVACET 507                                                            152 39% PTG     0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              1.22                                                                              +                                              1% MYVACET 707                                                            153 39% PTG     0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              1.23                                                                              +                                              1% MYVACET 908                                                            154 39% PTG     0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              nm  +                                              1% MYVEROL 18-07                                                          155 39% PTG     0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              nm  +                                              1% MYVEROL 18-35                                                          156 39% PTG     0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              nm  +                                              1% MYVEROL 18-99                                                          157 38% PTG     0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              1.21                                                                              +                                              1% paraffin                                                               158 38% PTG     0.10                                                                             2.64                                                                             -- 1.3                                                                              1.1                                                                              1.18                                                                              +                                              2% paraffin                                                               159 49% PEG(T) (70/30)                                                                        0.10                                                                             2.64                                                                             -- 1.3                                                                              0.6                                                                              0.89                                                                              +                                              1% MYVAPLEX 600                                                           __________________________________________________________________________

                                      TABLE XIII                                  __________________________________________________________________________    Mechanical Properties, Tear Strength, Water Vapor Transmission Rates of       Films                                                                         Prepared from Cellulose Ester/Polyester Blends Containing Hydrophobic         Additives                                                                                            Tangent                                                                            Tensile                                                                            Tear WVTR                                        Polyester/Hydrophobic                                                                     Elongation                                                                           Modulus                                                                            Strength                                                                           Strength                                                                           (g mil/100                              Entry                                                                             Additive    at Break (%)                                                                         (10.sup.5)                                                                         (10.sup.3)                                                                         (g/mil)                                                                            in.sup.2 -24 hours)                     __________________________________________________________________________    143 39.95% PTG  75     0.13 1.66 9.6  306                                         0.05% MYVAPLEX 600                                                        144 39.9% PTG   92     0.17 2.06 11.6 <500                                        0.1% MYVAPLEX 600                                                         145 39.75% PTG  78     0.16 1.64 9.5  244                                         0.25% MYVAPLEX 600                                                        146 39.5% PTG   93     0.11 2.10 14.9 227                                         0.5% MYVAPLEX 600                                                         147 39.25% PTG  81     0.11 1.67 12.8 171                                         0.75% MYVAPLEX 600                                                        148 39% PTG     71     0.11 1.47 10.8 103                                         1% MYVAPLEX 600                                                           149 38.5% PTG   75     0.12 1.71 14.0 159                                         1.5% MYVAPLEX 600                                                         150 38% PTG     62     0.11 1.45 9.8  178                                         2% MYVAPLEX 600                                                           151 39% PTG     82     0.11 1.76 12.7 200                                         1% MYVACET 507                                                            152 39% PTG     64     0.09 1.69 9.5  261                                         1% MYVACET 707                                                            153 39% PTG     75     0.09 2.39 12.6 258                                         1% MYVACET 908                                                            154 39% PTG     62     0.15 1.27 12.5 146                                         1% MYVEROL 18-07                                                          155 39% PTG     92     0.07 2.04 12.2 181                                         1% MYVEROL 18-35                                                          156 39% PTG     75     0.08 1.32 13.7 397                                         1% MYVEROL 18-99                                                          157 39% PTG     105    0.10 2.35 15.9 238                                         1% paraffin                                                               158 38% PTG     65     0.15 1.66 17.1 231                                         2% paraffin                                                               159 49% PEG(T)[70/30]                                                                         48     0.10 1.35 7.6  106                                         1% MYVAPLEX 600                                                           __________________________________________________________________________

The examples of Tables XII and XIII illustrate that hydrophobicadditives can be added to blends of cellulose esters and aliphaticpolyesters or aliphatic-aromatic copolyesters to control water vaportransmission rates of materials prepared from the blends without loss ofmechanical properties or tear strength. For example, the WVTR of thefilms prepared from a CAP/PTG blend containing 0.25-1% MYVAPLEX 600 wascontrolled between 244 to 103 g mil/100 in² -24 hours (cf entries143-146). With increasing hydrophobic additive, the WVTR decreased untilthe WVTR leveled off at around 1% additive.

EXAMPLE 8

Preparation of a 65/35 blend of CAP(DS_(Ac) =0.10, DS_(Pr)=2.64)/poly(tetramethylene glutarate) on the 30 mm W-P twin screwextruder was performed under the following conditions according to thegeneral procedure.

Feed rate for poly(tetramethylene glutarate)=15.0 lb/hr

Feed rate for CAP=28.0 lb/hr

Total output from extruder=43 lb/hr

Feed Line temperature=190° C.

RPM of the Screw=207

Torque=30%

Extruder zone temperatures: Zone 1=180° C.; Zones 2-7=230° C.

EXAMPLE 9

Other blends, including 10, 20, and 40 wt. % polytetramethyleneglutarate with CAP (DS_(Ac) =0.10, DS_(Pr) =2.64) were also prepared onthe W-P extruder according to the general procedure except that thepolyester was added by mixing solid poly(tetramethylene glutarate) withCAP(DS_(Ac) =0.10, DS_(Pr) =2.64) and feeding both materials into Zone 1of the extruder under otherwise similar conditions.

EXAMPLE 10

Blends prepared as in Examples 8 and 9 were molded on a Toyo 90injection molding machine under the following conditions. Theseconditions should not be considered the ideal conditions, but aretypical of those that can be used on blends of this type.

Nozzle temperature=200° C.

Zone 1 temperature=210° C.

Zone 2 temperature=210° C.

Zone 3 temperature=190° C.

Zone 4 temperature=180° C.

Melt temperature=215° C.

Injection and Hold Pressures=750 psig

Mold temperature=14° C.

Screw speed=75 rpm

EXAMPLE 11

The physical properties of the blends prepared as in Example 10 areshown in Table XIV as well as physical properties of the CAP containing12% monomeric plasticizer.

                  TABLE XIV                                                       ______________________________________                                        Physical Properties of Blends of CAP (DS.sub.Ac = 0.10,                       DS.sub.Pr = 2.64) and Poly(Tetramethylene Glutarate)                          Property   10%      20%    35%    40%  12%                                    (units)    PTG      PTG    PTG    PTG  DOA                                    ______________________________________                                        Tensile    7.9      5.3    2.8    2.3  4.76                                   Strength                                                                      (10.sup.3 psi)                                                                Elongation 14       41     72     93   27                                     at break (%)                                                                  Flexural   3.3      2.1     0.78   0.18                                                                              2.16                                   Modulus                                                                       (10.sup.5 psi)                                                                Izod Impact                                                                              1.7      4.6    15.4   12.9 7.43                                   23° C.                                                                            (C)      (C)    (PB)   (NB)                                        (ft-lb/in)                                                                    HDT        81       54     41     NT   67                                     (°C.)                                                                  ______________________________________                                    

This example demonstrates that aliphatic polyesters blend components arevery effective non-volatile, non-extractable polymeric additives. Theseblends offer many superior physical properties relative to a CAPcontaining a monomeric plasticizer. For example, relative to the a CAPcontaining 12% DOA, the blend containing 10% PTG has superior tensilestrength, flexural modulus, and a higher heat deflection temperature.

EXAMPLE 12

The physical properties blends prepared as in Example 10 are shown inTable XIV.

                                      TABLE XV                                    __________________________________________________________________________    Physical Properties of Blends of CAP (DS.sub.Ac = 0.10, DS.sub.Pr = 2.64)     and Aliphatic-Aromatic                                                        Polyesters as well as Physical Properties of the CAP containing 12%           Monomeric Plasticizer                                                         Property                                                                             8% PEG(T)                                                                            16% PEG(T)                                                                           24% PEG(T)                                                                           8% PTG(T)                                                                            16% PTG(T)                                                                           24% PTG(T)                          (units)                                                                              [70/30]                                                                              [70/30]                                                                              [70/30]                                                                              [60/40]                                                                              [60/40]                                                                              [60/40]                                                                              12% DOA                      __________________________________________________________________________    Tensile                                                                              8.32   8.79   7.46   8.67   8.64   7.79   4.76                         Strength                                                                      (10.sup.3 psi)                                                                Elongation                                                                           8      8      14     11     11     17     27                           at break (%)                                                                  Flexural                                                                             3.53   3.23   2.52   3.43    3.25  2.72   2.16                         Modulus                                                                       (10.sup.5 psi)                                                                Flexural                                                                             10.43  9.98   7.97   10.82  10.32  8.74   5.67                         Strength                                                                      (10.sup.3 psi)                                                                Izod Impact                                                                          1.63   1.70   1.82   3.00   2.69   2.96   7.43                         23° C.                                                                 (ft-lb/in)                                                                    Izod Impact                                                                          0.77   0.76   0.25   2.16   2.11   2.23   2.94                         -40° C.                                                                (ft-lb/in)                                                                    HDT    82     68     52     93     74     59     67                           66 psi                                                                        (°C.)                                                                  __________________________________________________________________________

This example demonstrates that aliphatic-aromatic polyesters blendcomponents are very effective non-volatile, non-extractable polymericadditives. These blends offer many superior physical properties relativeto a CAP containing a monomeric plasticizer. For example, relative tothe a CAP containing 12% DOA, all of the above blends at similar polymercontent have superior tensile strengths, flexural moduli, and flexuralstrengths as well as higher heat deflection temperatures. This examplealso teaches some of the physical property differences between amiscible, i.e., PEG(T) [70/30], cellulose ester/aliphatic-aromatic blendand a partially miscible, i.e., PEG(T) [60/40], celluloseester/aliphatic-aromatic blend. In general, the partially miscible blendoffers superior Izod impact strengths, particularly at -40° C.

EXAMPLE 13

                                      TABLE XVI                                   __________________________________________________________________________    Inherent Viscosity, Water Vapor Transmission Rates, Mechanical                Properties,                                                                   and Tear Strength of Films Prepared From Aliphatic-Aromatic Copolyesters                     Elongation                                                                          Tangent                                                                            Tensile                                                                            Tear     WVTR                                                 at Break                                                                            Modulus                                                                            Strength                                                                           Strength (g/100                                Entry                                                                             Polyester  (%)   (10.sup.5 psi)                                                                     (10.sup.3 psi)                                                                     (g/mil)                                                                            IV  in.sup.2 -24 hours)                   __________________________________________________________________________    160 PHG(T) [50/50]                                                                           357   0.09 0.73  26  0.72                                                                              65                                    161 PTG(T) [60/40]                                                                           908   0.05 1.95 214  1.15                                                                              137                                   162 PTG(T) [40/60]                                                                           642   0.23 3.07 115  0.94                                                                              52                                    163 PTS(T) [70/30]                                                                           722   0.41 4.48  59  nm  nm                                    164 PTS(T) [85/15]                                                                           732   0.28 3.99  42  1.03                                                                              42                                    165 PTG(T) [55/45]                                                                           738   0.08 3.54 142  1.11                                                                              nm                                    166 PTG(T)(D) [50/45/5]                                                                      927   0.05 5.22 126  1.23                                                                              nm                                    __________________________________________________________________________

These examples illustrate that films prepared from aliphatic-aromaticcopolyesters have very high elongation, high tear strengths, low WVTR,and low moduli and hence are useful in film applications.

EXAMPLE 14 The Physical Properties of AAPE Molded Bars

                  TABLE XVII                                                      ______________________________________                                        Physical Properties of AAPE                                                   Property     PTS(T)    PTS(T)     PTG(T)                                      (units)      [85/15]   [70/30]    [50/50]                                     ______________________________________                                        Tensile      2.89      1.79       1.51                                        Strength                                                                      (10.sup.3 psi)                                                                Elongation   482       384        437                                         at break (%)                                                                  Flexural     0.57      0.20       0.13                                        Modulus                                                                       (10.sup.5 psi)                                                                Izod Impact  6.0 (NB)  6.5 (NB)   3.2 (NB)                                    23° C.                                                                 (ft-lb/in)                                                                    Izod Impact  0.44 (CB) 0.86 (CB)  8.23 (NB)                                   -40° C.                                                                (ft-lb/in)                                                                    ______________________________________                                    

This example demonstrates that AAPEs have very high elongation at break,low flexural modulus and excellent Izod Impacts.

EXAMPLE 15

A variety of conditions are available for producing melt blown filmsfrom the blends of this invention. Temperature set points for theextruders can vary depending on the level of additives, if any. For thisexample, all heater zones were set between 190° and 200° C. with a screwrpm of 25 to 30. This produced a measured melt temperature of 183° C.Heater temperatures must be. increased, especially in the die area, by5° to 10° C. if higher levels of TiO₂ (or any antiblocks such as talc ordiatomaceous earth) are used in order to prevent clogging of the die.Temperature settings will also vary depending on the type of screw usedand the size of the extruder. The preferred temperatures are 175°-215°C. Blowing conditions can be characterized by the blow up ratio (BUR),the ratio of bubble diameter to die diameter which gives an indicationof hoop or transverse direction (TD) stretch; or the draw-down ratio(DDR), which is an indication of the axial or machine direction (MD)stretch. If the BUR and DDR are equal then the amount of stretch in theMD and TD is approximately the same resulting in "balanced" film.

Blown film was produced from a blend consisting of 98% of a 60/40 blendof cellulose acetate propionate (DS_(Ac) =0.10, DS_(Pr) =2.64) andpoly(tetramethylene glutarate), and 2% TiO₂. The TiO₂, added in the formof a masterbatch (blended at a level of 20% and pelletized), was addedin order to obtain an opaque film. The blown film was produced using alaboratory scale blown film line which consisted of a Killion 1.25 inchextruder with a 15:1 gear reducer. The screw was a Maddock mixing typewith an L/D of 24 to 1 although a general purpose screw has also beenused. Compression ratio for the mixing screw was 3.5:1. A 1.21 inch diewith a 5 mil die gap was used. The air ring was a Killion single-lip,No. 2 type. Prior to processing, the blends were dried overnight at 50°C. in dehumidified air dryers.

For this example, the BUR was 2.20 and the DDR was 1.13 resulting in afilm with an average thickness of 2 mils. This produced a film withaverage tear strengths of 8.9 and 7.5 g/mil in the MD and TD,respectively. Additionally, elongation to break values for thesedirections are 101 and 79%, tangent moduli are 30 and 24 ksi, and breakstresses are 3.9 and 3.6 ksi. BUR values have been tried ranging from 2to 3.9 and DDR values from 0.5 to 20 by changing blow conditions andalso going to a thicker die gap. Increasing these parameters generallyresults in improved properties except for % elongation which is reduced.For example, a 0.5 mil film with a BUR of 2.76 and a DDR of 3.89 hadaverage tear strengths of 31.3 and 29.7 g/mil, elongation to breakvalues of 74 and 37%, moduli of 57 and 86 ksi, and break stresses of 3.2and 4.9 ksi for the MD and TD, respectively.

EXAMPLE 16

Blown film was produced from blends consisting of cellulose acetatepropionate (DS_(Ac) =0.10, DS_(Pr) =2.64) and poly(tetramethyleneglutarate-co-terephthalate). The blown film was produced using alaboratory scale blown film line which consisted of a Killion 1.25 inchextruder with a 15:1 gear reducer. The screw was a Maddock mixing typewith an L/D of 24 to 1 although a general purpose screw has also beenused. Compression ratio for the mixing screw was 3.5:1. A 1.21 inch diewith a 25 mil die gap was used. The air ring was a Killion single-lip,No. 2 type. Prior to processing, the blends were dried overnight at 50°C. in dehumidified air dryers. The results are given in Table XVII.

                                      TABLE XVIII                                 __________________________________________________________________________    Conditions and Results for Blown Film of a Cellulose Acetate Propionate       and                                                                           Poly(tetramethylene Glutarate-co-terephthalate)                                          Film         Tear.sup.c Tangent.sup.c                                         Thickness    Strength                                                                           Elongation.sup.c                                                                    Modulus                                    Entry.sup.a                                                                       Description.sup.b                                                                    (mils)                                                                              BUR                                                                              DDR (q/mil)                                                                            (%)   (ksi)                                      __________________________________________________________________________    167 35/65  2.41  3.2                                                                              3.9 50.8  80   55                                             [50/50]             13.4 156   37                                         168 25/75  1.21  3.1                                                                              8.1 57.7 121   24                                             [50/50]             49.0 257   19                                         169 35/65  2.11  2.6                                                                              4.6 74.8 123   36                                             [55/45]             15.5 161   33                                         170 25/75  1.95  2.6                                                                              4.9 101.1                                                                              121   35                                             [55/45]             59.7 344   23                                         171 35/65  2.19  2.6                                                                              4.4 36.6 124   18                                             [60/40]             29.4 178    9                                         __________________________________________________________________________     .sup.a Each sample contained inorganics.                                      .sup.b The first ratio (e.g., 35/65) is the ratio of cellulose ester to       copolyester in the blend. The second ratio (e.g., [50/50]) is the ratio o     glutarate to terephthalate in the copolyester.                                .sup.c The first value is for the machine direction and the second value      is for the transverse direction.                                         

The entries of this example demonstrate that film blown from blends ofcellulose acetate propionate and aliphatic-aromatic copolyesters havevery high tear strengths and elongation at break. Moreover, physicalproperties such as tear strength can be high in one direction or can beroughly equal in both directions demonstrating that this film can beoriented. In general, a balanced film is obtained by choice of theDDR/BUR ratio.

EXAMPLE 17

An 80/20 blend of cellulose acetate propionate (DS_(Ac) =0.10, DS_(Pr)=2.64)/poly(tetramethylene glutarate) was used to spin fibers using a 54hole round and Y jet (55 micron equivalent diameter) at an extrusiontemperature of 215° C. and a takeup of 250 m/m or 600 m/m. Packages weredoffed and plied together onto cones making 270 filament yarn. A twostep draw process was used to make drawn fiber. Table XV givesrepresentative data for both drawn and undrawn fiber. Photomicrographsshowed that the fibers had excellent cross-sectional stability.

                  TABLE XIX                                                       ______________________________________                                        Strand Tensiles of Fiber Melt-Spun From an 80/20 Blend of                     Cellulose Acetate Propionate/Poly(Tetramethylene Glutarate)                        Temp                                  Tough-                                  (°C.)/                  Modulus                                                                              ness                               En-  Draw                    Elonga-                                                                              g/     g/                                 try  Ratio    Denier  Tenacity                                                                             tion   Denier Denier                             ______________________________________                                        172  undrawn  905     0.42   38     16     0.14                               172B 70/1.82  486     0.98    4     45     0.02                               173  undrawn  1478    0.54   49     16     0.21                               173B 85/1.75  892     0.93    5     41     0.03                               174  undrawn  877     0.66   26     19     0.14                               174B 70/1.33  673     1.02    4     42     0.03                               175  undrawn  898     0.55   26     17     0.12                               175B 70/1.40  655     0.88    3     42     0.01                               ______________________________________                                    

Biodegradation Studies

Although it is evident that polyhydroxyalkanoates are biodegradableunder the appropriate conditions, it is not known in the art thatcellulose esters are biodegradable since it is widely believed that theacyl substituents shield the cellulose backbone from microbial attack.We have found that when films of cellulose acetate having a degree ofsubstitution of 1.7 were immersed in the Tennessee Eastman (Kingsport,Tenn., U.S.A.) wastewater treatment facility, extensive degradation ofthe films occurred within 27 days. In addition, a culture consisting ofa mixed population of microbes isolated from the activated sludgeobtained from the same wastewater treatment facility were grown in thepresence of films of the same cellulose acetate (DS=1.7). In this case,extensive degradation of the cellulose acetate films was observed after5 days. FIGS. 1A, 1B, 2A, and 2B show scanning electron microscopy (SEM)photographs of the two sides of cellulose acetate films formed bydrawing a film from a solution consisting of 20% cellulose acetate(DS=1.7) by weight in a 50/50 mixture of water/acetate. FIGS. 1A and 2Aare of a control film while FIGS. 1B and 2B are of a film on which theculture, consisting of a mixed population of microbes isolated from theactivated sludge, were grown for 4 days. In FIGS. 1B and 2B, extensivedegradation of the cellulose acetate film is evident. Comparison of thecontrol films in FIGS. 1A and 2A shows that the film sides aredifferent. FIG. 1A shows the outer, smooth surface of the film whichresults from shearing by the draw blade while FIG. 2A shows the inner,rough surface of the film which was in contact with the surface on whichthe film was cast. Comparison of FIGS. 1B and 2B shows that the rough orinner side of the film was more extensively degraded. A rough surfacearea promotes attachment of the bacteria leading to a more rapid rate ofdegradation. Processes, such as foamed films and the like, which promoterough surfaces are desirable in the practice of this invention. FIGS. 3and 4 show SEM photographs of the smooth and rough sides of a celluloseacetate film from which the bacteria were not washed. In addition toshowing extensive pitting of the film surface due to degradation of thecellulose acetate, these films show the attached microbes in thecavities where degradation is occurring.

In vitro Enrichment System: fresh composite samples of activated sludgeare obtained from the AA 03 aeration basins in the Tennessee Eastman(Kingsport, Tenn., U.S.A.) wastewater treatment plant which has a designcapacity of receiving 25 million gallons of waste per day with BODconcentration up to 200,000 pounds per day. The major waste componentsconsist largely of methanol, ethanol, isopropanol, acetone, acetic acid,butyric acid, and propionic acid. The sludge operating temperatures varybetween 35° C. to 40° C. In addition, a dissolved oxygen concentrationof 2.0 to 3.0 and a pH of 7.1 are maintained to insure maximaldegradation rates. The activated sludge serves as the starting inoculumfor the stable mixed population of microbes used in this invention. Astable population is obtained by serially transferring the initialinoculum (5% v/v) to a basal salt media containing glucose orcellobiose, acetate, and cellulose acetate (DS=2.5).

Cellulose ester film degrading enrichments are initiated in a basalsalts medium containing the following ingredients per liter: 50 mL ofPfennig's Macro-mineral solution, 1.0 mL of Pfennig's trace elementsolution, 0.1% (wt/vol) Difco yeast extract, 2 mM Na₂ SO₄, 10 mM NH₄ C₁which supplements the ammonia levels provided by Pfennig's Macro-mineralsolution, 0.05% (wt/vol) cellobiose, 0.05% (wt/vol) NaOAc. This solutionis adjusted to pH 7.0 and a final volume of 945 mL before beingautoclaved at 121° C. at 15 psi for 15 minutes. After cooling to roomtemperature, 50 mL of sterile 1M phosphate buffer and 5 mL of a complexvitamin solution which has been filtered through a 0.02 mm filter areadded. The test cellulosic film is then added and the flask isinoculated (5% v/v) with a stable mixed population enrichment. The flaskis placed in a New Brunswick incubator and held at 30° C. and 250 rpmfor the appropriate period. Initially, the films are often observed toturn cloudy and to be coated with a yellow affinity substance (CurrentMicrobiology, 9, 195 (1983)), which is an indication of microbialactivity. After 4 to 12 days, the films are broken into small pieces atwhich time they are harvested by pouring the media through a filterfunnel. The pieces are collected and washed with water. The film piecesare suspended in a neutral detergent solution at 90° C. for 30-60minutes before washing extensively with water. The films are placed in avacuum oven at 40° C. until dry before weighing. In each experiment,control experiments are conducted in which the films are subjected tothe same experimental protocol except inoculation with the microbes.

Cellulose Acetate, DS=1.7.

    ______________________________________                                                                          %                                           Film     Original      Final      Weight                                      Number   Weight (mg)   Weight (mg)                                                                              Loss                                        ______________________________________                                         1*      190           181        5                                            2*      233           220        6                                            3*      206           196        5                                            4       134           2          99                                           5       214           35         84                                           6       206           16         92                                           7*      195           184        5                                            8*      187           175        6                                            9       177           3          98                                          10       181           5          97                                          11*      167           164        2                                           12*      174           173        1                                           13*      188           185        2                                           14       192           30         84                                          15       154           5          97                                          ______________________________________                                    

Films 1-6, 7-10, and 11-15 represent the results for three separateexperiments. Films 1-6 and 11-15 are shaken for 4 days while Films 7-10are shaken for 5 days. The films with the * represent control films.

In every case, weight loss of 84-99% is observed for the inoculatedfilms and only 0.6-6.4% for the control films.

Cellulose Acetate, DS=2.5.

    ______________________________________                                                                          %                                           Film     Original      Final      Weight                                      Number   Weight (mg)   Weight (mg)                                                                              Loss                                        ______________________________________                                        1*       135           136        0                                           2*       161           161        0                                           3*       132           131        0.8                                         4*       147           148        0                                           5        146           40         73                                          6        169           60         65                                          7        175           81         54                                          8        157           36         77                                          ______________________________________                                    

Each film is shaken for 12 days. The films with the * represent controlfilms. In every case, weight losses of 54-77% are observed for theinoculated films and 0-0.8% for the control films. As expected, thefilms with a higher degree of substitution exhibit greater resistance tomicrobial attack.

Wastewater Treatment Studies: Fifteen numbered cylinders, such as theone shown in FIG. 5, containing one cellulose acetate film each areattached to a steel cable and suspended in Tennessee Eastman's AD02basin. Films 1-4 are harvested after 21 days while Films 5-14 areharvested after 27 days. The harvested films are suspended in a neutraldetergent solution at 90° C. for 30-60 minutes before washingextensively with water. The films are placed in a vacuum oven at 40° C.until dry before weighing.

Cellulose Acetate, DS=1.7.

    ______________________________________                                        Biodegradation of Cellulose Acetate (DS = 1.7)                                In Wastewater Treatment Plant                                                               Final  %                    % Thick-                            Film Original Wt.    Wt.  Original                                                                              Final   ness                                No.  Wt. (mg) (mg)   Loss Thickness                                                                             Thickness                                                                             Loss                                ______________________________________                                        1    223      176    21   6.40    5.28    18                                  2    217      172    21   6.33    5.59    12                                  3    187      150    20   5.61    5.30     6                                  4    249      200    20   5.96    5.48     8                                  5    186      51     73   5.56    4.08    21                                  6    243      75     69   6.95    4.78    31                                  7    220      62     72   6.35    --      --                                  8    243      78     68   6.29    4.55    28                                  9    201      19     91   5.40    4.30    19                                  10   146      28     81   5.97    4.08    32                                  11   201      21     90   5.79    3.83    34                                  12   160      44     73   5.66    4.65    18                                  13   197      70     65   6.59    4.93    25                                  14   199      50     75   5.71    4.92    14                                  ______________________________________                                    

The films tested after 21 days show a weight loss of 20-21% while thefilms tested after 27 days show a weight loss of 65-91%. The large lossin film weight and thickness between days 21 and 27 is typical.Generally, an induction period is observed during which microbialattachment is occurring. When the bacteria are attached and enoughdegradation has occurred to expose more surface area, the rate ofdegradation increases. Films 2-4 are intact enough so that testing ofmechanical properties and comparison to control films (A-C) is possible:

    ______________________________________                                        Film       Tangent      Tensile                                               Number     Modulus (10.sup.5 psi)                                                                     Strength (10.sup.3 psi)                               ______________________________________                                        2          1.47         2.62                                                  3          1.25         1.49                                                  4          1.44         2.62                                                  A          2.63         4.85                                                  B          2.91         6.04                                                  C          2.41         5.09                                                  ______________________________________                                    

In each case, substantial loss in the tangent modulus and tensilestrength is observed which illustrates how the microbial degradation ofthe test films leads to loss in film properties.

Compost Biodegradation Assays: Composting can be defined as themicrobial catalyzed degradation and conversion of solid organic wasteinto soil. One of the key characteristics of compost piles is that theyare self heating; heat is a natural by-product of the metabolicbreakdown of organic matter. Depending upon the size of the pile, or itsability to insulate, the heat can be trapped and cause the internaltemperature to rise.

Efficient degradation within compost piles relies upon a naturalprogression or succession of microbial populations to occur. Initiallythe microbial population of the compost is dominated by mesophilicspecies (optimal growth temperatures between 20°-45° C.). The processbegins with the proliferation of the indigenous mesophilic microfloraand metabolism of the organic matter. This results in the production oflarge amounts of metabolic heat which raises the internal piletemperatures to approximately 55°-65° C. The higher temperature acts asa selective pressure which favors the growth of thermophilic species onone hand (optimal growth range between 45°-60° C.), while inhibiting themesophiles on the other. Although the temperature profiles are oftencyclic in nature, alternating between mesophilic and thermophilicpopulations, municipal compost facilities attempt to control theiroperational temperatures between 55°-60° C. in order to obtain optimaldegradation rates. Municipal compost units are also typically aerobicprocesses, which supply sufficient oxygen for the metabolic needs of themicroorganisms permitting accelerated biodegradation rates.

In order to assess the biodegradation potential of the test films,small-scale compost units were employed to simulate the active treatmentprocesses found in a municipal solid waste composter. These bench-scaleunits displayed the same key features that distinguish the large-scalemunicipal compost plants. The starting organic waste was formulated tobe representative of that found in municipal solid waste streams: acarbon to nitrogen ratio of 25:1, a 55% moisture content, a neutral pH,a source of readily degradable organic carbon (e.g., cellulose, protein,simple carbohydrates, and lipids), and had a particle size that allowedgood air flow through the mass. Prior to being placed in a compost unit,all test films were carefully dried and weighed. Test films were mixedwith the compost at the start of an experiment and incubated with thecompost for 10 to 15 days. The efficiency of the bench scale compostunits was determined by monitoring the temperature profiles and dryweight disappearance of the compost. These bench scale units typicallyreached 60°-65° C. within 8 hours. After 15 days of incubation there wastypically a 40% dry weight loss in the compost. Films were harvestedafter 10 or 15 days of incubation and carefully washed, dried, andweighed to determine weight loss. The following is representative of theresults of such composting experiments:

    ______________________________________                                                                    Film                                                                  Weight  Thickness                                         Film Composition    Loss    (mil)                                             ______________________________________                                        Composting Results: 15 Day Composting Trial                                   55/45 CAP(DS = 2.15)/PEG                                                                          36%     0.63                                              55/45 CAP(DS = 2.15)/PTG                                                                          29%     0.68                                              60/40 CAP(DS = 2.7)/PTG +                                                                         16%     2.77                                              1% microcrystalline cellulose                                                 60/40 CAP(DS = 2.7)/PTG                                                                           14%     2.38                                              Composting Results: 10 Day Composting Trial                                   45/55 CAP(DS = 2.09)/PEG                                                                          47%     0.45                                              55/45 CAP(DS = 2.15)/PEG                                                                          29%     0.61                                              55/45 CAP(DS = 2.49)/PTG                                                                          26%     0.56                                              60/40 CAP(DS = 2.7)/PTG +                                                                         22%     0.98                                              2.5% CaCO.sub.3                                                               60/40 CAP(DS = 2.7)/PTG +                                                                         20%     5.31                                              2% cellulose monoacetate                                                      PTG(T) [60/40]      17%     2.95                                              PTG(T)(D) [60/35/15]                                                                              16%     19.2                                              ______________________________________                                    

The invention has been described in detail with particular reference topreferred embodiments thereof, but it will be understood that variationsand modifications can be effected within the spirit and scope of theinvention. Moreover, all patents, patent applications (published orunpublished, foreign or domestic), literature references or otherpublications noted above are incorporated herein by reference for anydisclosure pertinent to the practice of this invention.

We claim:
 1. A binary blend comprising:(A) about 5% to about 98% of a C₁-C₁₀ ester of cellulose having a number of substituents peranhydroglucose unit of about 1.7 to 3.0 and an inherent viscosity ofabout 0.2 to about 3.0 deciliters/gram as measured at a temperature of25° C. for a 0.5 g sample in 100 ml of a 60/40 parts by weight solutionof phenol/tetrachloroethane, and (B) about 2% to about 95% of analiphatic-aromatic copolyester having an inherent viscosity of about 0.2to about 2.0 deciliters/gram as measured at a temperature of 25° C. fora 0.5 g sample in 100 ml of a 60/40 parts by weight solution ofphenol/tetrachloroethane, said percentages being based on the weight ofcomponent (A) plus component (B).
 2. The blend of claim 1 wherein saidester of cellulose is cellulose acetate, cellulose propionate, cellulosebutyrate, cellulose acetate propionate, cellulose acetate butyrate, orcellulose propionate butyrate.
 3. The blend of claim 2 wherein saidester of cellulose is cellulose acetate propionate or cellulose acetatebutyrate.
 4. The blend of claim 3 wherein said ester of cellulose iscellulose acetate propionate.
 5. The blend of claim 1 wherein saidaliphatic aromatic copolyester comprises repeat units of: ##STR6##wherein R⁴ and R⁷ are selected from one or more of the groups consistingof C₂ -C₁₂ alkylene or oxyalkylene; C₂ -C₁₂ alkylene or oxyalkylenesubstituted with one to four substituents independently selected fromthe group consisting of halo, C₆ -C₁₀ aryl, and C₁ -C₄ alkoxy; C₅ -C₁₀cycloalkylene; C₅ -C₁₀ cycloalkylene substituted with one to foursubstituents independently selected from the group consisting of halo,C₆ -C₁₀ aryl, and C₁ -C₄ alkoxy; R⁵ is selected from one or more of thegroups consisting of C₀ -C₁₂ alkylene; C₂ -C₁₂ oxyalkylene; C₂ -C₁₂alkylene or oxyalkylene substituted with one to four substituentsindependently selected from the group consisting of halo, C₆ -C₁₀ aryl,and C₁ -C₄ alkoxy; C₅ -C₁₀ cycloalkylene; and C₅ -C₁₀ cycloalkylenesubstituted with one to four substituents independently selected fromthe group consisting of halo, C₆ -C₁₀ aryl, and C₁ -C₄ alkoxy; R⁶ isselected from one or more of the groups consisting of C₆ -C₁₀ aryl, C₆-C₁₀ aryl substituted with one to four substituents independentlyselected from the group consisting of halo, C₁ -C₄ alkyl, and C₁ -C₄alkoxy.
 6. The blend of claim 1 wherein aliphatic-aromatic copolyesterhas an inherent viscosity of about 0.4 to about 1.2 as measured at atemperature of 25° C. for a 0.5 gram sample in 100 ml of a 60/40 byweight solution of phenol/tetrachloroethane.
 7. The blend of claim 6wherein aliphatic-aromatic copolyester comprises 15 to 600 repeat units.8. The blend of claim 1 wherein the cellulose ester has an inherentviscosity of about 0.5 to about 1.5 deciliters/gram.
 9. The blend ofclaim 3 wherein the cellulose ester has a number of substituents peranhydroglucose unit of from about 2.1 to about 2.85.
 10. The blend ofclaim 4 wherein the ester of cellulose is cellulose acetate propionatehaving a number of substituents per anhydroglucose unit from about 2.50to about 2.75 and the number of substituents per anhydroglucose unit ofacetyl ester is from about 4-30% of the total ester content.
 11. Theblend of claim 2 wherein the glass transition temperature of thecellulose ester is from about 85°-210° C.
 12. The blend of claim 4wherein the glass transition temperature of the cellulose ester is fromabout 140°-180° C.
 13. The blend of claim 5 wherein R⁴ or R⁷ is selectedfrom the group consisting of C₂ -C₆ alkylene, C₄ -C₈ oxyalkylene, or C₅-C₁₀ cycloalkylene; R⁵ is selected from the group consisting of C₀ -C₄alkylene, C₂ -C₄ oxyalkylene, or C₅ -C₁₀ cycloalkylene; R⁶ is selectedfrom the group consisting of C₆ -C₁₀ aryl.
 14. The blend of claim 5wherein the mole % of R⁵ in the copolymer is from about 30 to 95%, andthe mole % of R⁶ is from about 5 to 70%.
 15. The blend of claim 14wherein the mole % of R⁵ in the copolymer is from about 45 to 85% andthe mole % of R⁶ is from about 15 to 55%.
 16. The miscible blend ofclaim 15 wherein R⁵ is C3 and the mole % of R⁵ in the copolymer is fromabout 70 to 85%, and the mole % of R⁶ is from about 15 to 30%.
 17. Thepartially miscible blend of claim 15 wherein R⁵ is C3 and the mole % ofR⁵ in the copolymer is from about 45 to 60%, and the mole % of R⁶ isfrom about 40 to 55%.
 18. The blend of claim 9 wherein component (B) ispresent in an amount of about 5 to 75% and component (A) is present inan amount of about 25 to 95%.
 19. The blend of claim 5 wherein saidaliphatic-aromatic copolyester is prepared from any polyester formingcombination or combinations of dicarboxylic acids or derivativesthereof, and diols, said dicarboxylic acids are selected from the groupconsisting of the following diacids: malonic, succinic, glutaric,adipic, pimelic, azelaic, sebacic, fumaric, 2,2-dimethyl glutaric,suberic, 1,3-cyclopentanedicarboxylic, 1,4-cyclohexanedicarboxylic,1,3-cyclohexanedicarboxylic, diglycolic, itaconic, maleic,2,5-norbornanedicarboxylic, 1,4-terephthalic, 1,3-terephthalic,2,6-naphthalene dicarboxylic, 1,5-naphthalene dicarboxylic, and esterforming derivatives thereof, and combinations thereof; and said diolsare selected from the group consisting of ethylene glycol, diethyleneglycol, propylene glycol, 1,3-propanediol, 2,2-dimethyl-1,3-propanediol,1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,2,2,4-trimethyl-1,6-hexanediol, thiodiethanol,1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol,2,2,4,4-tetramethyl-1,3-cyclobutanediol, triethylene glycol,tetraethylene glycol, di-, tri-, tetrapropylene glycol, and combinationsthereof.
 20. The blend of claim 19 wherein the aliphatic-aromaticpolyester is poly(ethylene glutarate-co-terephthalate) and the mole % ofterephthalate is 15-55%.
 21. The blend of claim 19 wherein thealiphatic-aromatic copolyester is poly(tetramethyleneglutarate-co-terephthalate) and the mole % of terephthalate is 15-55%.22. The blend of claim 19 wherein the aliphatic-aromatic copolyester ispoly(tetramethylene glutarate-co-terephthalate-co-diglycolate) and themole % of terephthalate is 15-55% and the mole % of diglycolate is1-10%.
 23. The blend of claim 19 wherein the aliphatic-aromaticcopolyester is poly(tetramethylene adipate-co-terephthalate) and themole % of terephthalate is 15-55%.
 24. The blend of claim 19 wherein thealiphatic-aromatic copolyester is poly(ethyleneadipate-co-terephthalate) and the mole % of terephthalate is 15-55%. 25.The blend of claim 19 wherein the aliphatic-aromatic copolyester ispoly(tetramethylene succinate-co-terephthalate) and the mole % ofterephthalate is 15-55%.
 26. The blend of claim 19 wherein thealiphatic-aromatic copolyester is poly(ethylenesuccinate-co-terephthalate) and the mole % of terephthalate is 15-55%.27. The blend of claim 19 wherein the aliphatic-aromatic copolyester ispoly(ethylene glutarate-co-naphthalene dicarboxylate) and the mole % ofnaphthalene dicarboxylate is 15-55%.
 28. The blend of claim 19 whereinthe aliphatic-aromatic copolyester is poly(tetramethyleneglutarate-co-naphthalene dicarboxylate) the mole % of naphthalenedicarboxylate is 15-55%.
 29. The blend of claim 19 wherein thealiphatic-aromatic copolyester is poly(tetramethyleneadipate-co-naphthalene dicarboxylate) and the mole % of naphthalenedicarboxylate is 15-55%.
 30. The blend of claim 19 wherein thealiphatic-aromatic copolyester is poly(ethylene adipate-co-naphthalenedicarboxylate) and the mole % of naphthalene dicarboxylate is 15-55%.31. The blend of claim 19 wherein the aliphatic-aromatic copolyester ispoly(tetramethylene succinate-co-naphthalene dicarboxylate) and the mole% of naphthalene dicarboxylate is 15-55%.
 32. The blend of claim 19wherein the aliphatic-aromatic copolyester is poly(ethylenesuccinate-co-naphthalene dicarboxylate) and the mole % of naphthalenedicarboxylate is 15-55%.
 33. The blend of claim 1 additionallycomprising 0.001 to 50 weight %, based on the total weight of thecomposition, of at least one additional additive selected from the groupconsisting of a non-polymeric plasticizer, a thermal stabilizer, anantioxidant, a pro-oxidant, an acid scavenger, an ultraviolet lightstabilizer, a promoter of photodegradation, inorganics, and colorants.34. The blend of claim 33 wherein the inorganic is CaCO₃.
 35. The blendof claim 33 wherein the colorant is a polyester with 0.01 to 50% of acovalently bound dye.
 36. The blend of claim 1 wherein component (A) andcomponent (B) are miscible.
 37. The blend of claim 1 wherein component(A) and component (B) are partially miscible.